vivacity in our dreams; and hence all that motley group of ideas, which are
caused by them, called the ideas of imagination, with their various
associated trains, are in a very vivid manner acted over in the sensorium;
and these sometimes call into action the larger muscles, which have been
much associated with them; as appears from the muttering sentences, which
some people utter in their dreams, and from the obscure barking of sleeping
dogs, and the motions of their feet and nostrils.
This perpetual flow of the trains of ideas, which constitute our dreams,
and which are caused by painful or pleasurable sensation, might at first
view be conceived to be an useless expenditure of sensorial power. But it
has been shewn, that those motions, which are perpetually excited, as those
of the arterial system by the stimulus of the blood, are attended by a
great accumulation of sensorial power, after they have been for a time
suspended; as the hot-fit of fever is the consequence of the cold one. Now
as these trains of ideas caused by sensation are perpetually excited during
our waking hours, if they were to be suspended in sleep like the voluntary
motions, (which are exerted only by intervals during our waking hours,) an
accumulation of sensorial power would follow; and on our awaking a delirium
would supervene, since these ideas caused by sensation would be produced
with such energy, that we should mistake the trains of imagination for
ideas excited by irritation; as perpetually happens to people debilitated
by fevers on their first awaking; for in these fevers with debility the
general quantity of irritation being diminished, that of sensation is
increased. In like manner if the actions of the stomach, intestines, and
various glands, which are perhaps in part at least caused by or catenated
with agreeable sensation, and which perpetually exist during our waking
hours, were like the voluntary motions suspended in our sleep; the great
accumulation of sensorial power, which would necessarily follow, would be
liable to excite inflammation in them.
3. When by our continued posture in sleep, some uneasy sensations are
produced, we either gradually awake by the exertion of volition, or the
muscles connected by habit with such sensations alter the position of the
body; but where the sleep is uncommonly profound, and those uneasy
sensations great, the disease called the incubus, or nightmare, is
produced. Here the desire of moving the body is painfully exerted, by the
power of moving it, or volition, is incapable of action, till we awake.
Many less disagreeable struggles in our dreams, as when we wish in vain to
fly from terrifying objects, constitute a slighter degree of this disease.
In awaking from the nightmare I have more than once observed, that there
was no disorder in my pulse; nor do I believe the respiration is laborious,
as some have affirmed. It occurs to people whose sleep is too profound, and
some disagreeable sensation exists, which at other times would have
awakened them, and have thence prevented the disease of nightmare; as after
great fatigue or hunger with too large a supper and wine, which occasion
our sleep to be uncommonly profound. See No. 14, of this Section.
4. As the larger muscles of the body are much more frequently excited by
volition than by sensation, they are but seldom brought into action in our
sleep: but the ideas of the mind are by habit much more frequently
connected with sensation than with volition; and hence the ceaseless flow
of our ideas in dreams. Every one's experience will teach him this truth,
for we all daily exert much voluntary muscular motion: but few of mankind
can bear the fatigue of much voluntary thinking.
5. A very curious circumstance attending these our sleeping imaginations
is, that we seem to receive them by the senses. The muscles, which are
subservient to the external organs of sense, are connected with volition,
and cease to act in sleep; hence the eyelids are closed, and the tympanum
of the ear relaxed; and it is probable a similarity of voluntary exertion
may be necessary for the perceptions of the other nerves of sense; for it
is observed that the papillæ of the tongue can be seen to become erected,
when we attempt to taste any thing extremely grateful. Hewson Exper.
Enquir. V. 2. 186. Albini Annot. Acad. L. i. c. 15. Add to this, that the
immediate organs of sense have no objects to excite them in the darkness
and silence of the night, but their nerves of sense nevertheless continue
to possess their perfect activity subservient to all their numerous
sensitive connections. This vivacity of our nerves of sense during the time
of sleep is evinced by a circumstance, which almost every one must at some
time or other have experienced; that is, if we sleep in the daylight, and
endeavour to see some object in our dream, the light is exceedingly painful
to our eyes; and after repeated struggles we lament in our sleep, that we
cannot see it. In this case I apprehend the eyelid is in some degree opened
by the vehemence of our sensations; and, the iris being dilated, the optic
nerve shews as great or greater sensibility than in our waking hours. See
No. 15. of this Section.
When we are forcibly waked at midnight from profound sleep, our eyes are
much dazzled with the light of the candle for a minute or two, after there
has been sufficient time allowed for the contraction of the iris; which is
owing to the accumulation of sensorial power in the organ of vision during
its state of less activity. But when we have dreamt much of visible
objects, this accumulation of sensorial power in the organ of vision is
lessened or prevented, and we awake in the morning without being dazzled
with the light, after the iris has had time to contract itself. This is a
matter of great curiosity, and may be thus tried by any one in the
day-light. Close your eyes, and cover them with your hat; think for a
minute on a tune, which you are accustomed to, and endeavour to sing it
with as little activity of mind as possible. Suddenly uncover and open your
eyes, and in one second of time the iris will contract itself, but you will
perceive the day more luminous for several seconds, owing to the
accumulation of sensorial power in the optic nerve.
Then again close and cover your eyes, and think intensely on a cube of
ivory two inches diameter, attending first to the north and south sides of
it, and then to the other four sides of it; then get a clear image in your
mind's eye of all the sides of the same cube coloured red; and then of it
coloured green; and then of it coloured blue; lastly, open your eyes as in
the former experiment, and after the first second of time allowed for the
contraction of the iris, you will not perceive any increase of the light of
the day, or dazzling; because now there is no accumulation of sensorial
power in the optic nerve; that having been expended by its action in
thinking over visible objects.
This experiment is not easy to be made at first, but by a few patient
trials the fact appears very certain; and shews clearly, that our ideas of
imagination are repetitions of the motions of the nerve, which were
originally occasioned by the stimulus of external bodies; because they
equally expend the sensorial power in the organ of sense. See Sect. III. 4.
which is analogous to our being as much fatigued by thinking as by labour.
6. Nor is it in our dreams alone, but even in our waking reveries, and in
great efforts of invention, so great is the vivacity of our ideas, that we
do not for a time distinguish them from the real presence of substantial
objects; though the external organs of sense are open, and surrounded with
their usual stimuli. Thus whilst I am thinking over the beautiful valley,
through which I yesterday travelled, I do not perceive the furniture of my
room: and there are some, whose waking imaginations are so apt to run into
perfect reverie, that in their common attention to a favourite idea they do
not hear the voice of the companion, who accosts them, unless it is
repeated with unusual energy.
This perpetual mistake in dreams and reveries, where our ideas of
imagination are attended with a belief of the presence of external objects,
evinces beyond a doubt, that all our ideas are repetitions of the motions
of the nerves of sense, by which they were acquired; and that this belief
is not, as some late philosophers contend, an instinct necessarily
connected only with our perceptions.
7. A curious question demands our attention in this place; as we do not
distinguish in our dreams and reveries between our perceptions of external
objects, and our ideas of them in their absence, how do we distinguish them
at any time? In a dream, if the sweetness of sugar occurs to my
imagination, the whiteness and hardness of it, which were ideas usually
connected with the sweetness, immediately follow in the train; and I
believe a material lump of sugar present before my senses: but in my waking
hours, if the sweetness occurs to my imagination, the stimulus of the table
to my hand, or of the window to my eye, prevents the other ideas of the
hardness and whiteness of the sugar from succeeding; and hence I perceive
the fallacy, and disbelieve the existence of objects correspondent to those
ideas, whose tribes or trains are broken by the stimulus of other objects.
And further in our waking hours, we frequently exert our volition in
comparing present appearances with such, as we have usually observed; and
thus correct the errors of one sense by our general knowledge of nature by
intuitive analogy. See Sect. XVII. 3. 7. Whereas in dreams the power of
volition is suspended, we can recollect and compare our present ideas with
none of our acquired knowledge, and are hence incapable of observing any
absurdities in them.
By this criterion we distinguish our waking from our sleeping hours, we can
voluntarily recollect our sleeping ideas, when we are awake, and compare
them with our waking ones; but we cannot in our sleep _voluntarily_
recollect our waking ideas at all.
8. The vast variety of scenery, novelty of combination, and distinctness of
imagery, are other curious circumstances of our sleeping imaginations. The
variety of scenery seems to arise from the superior activity and excellence
of our sense of vision; which in an instant unfolds to the mind extensive
fields of pleasurable ideas; while the other senses collect their objects
slowly, and with little combination; add to this, that the ideas, which
this organ presents us with, are more frequently connected with our
sensation than those of any other.
9. The great novelty of combination is owing to another circumstance; the
trains of ideas, which are carried on in our waking thoughts, are in our
dreams dissevered in a thousand places by the suspension of volition, and
the absence of irritative ideas, and are hence perpetually falling into new
catenations. As explained in Sect. XVII. 1. 9. For the power of volition is
perpetually exerted during our waking hours in comparing our passing trains
of ideas with our acquired knowledge of nature, and thus forms many
intermediate links in their catenation. And the irritative ideas excited by
the stimulus of the objects, with which we are surrounded, are every moment
intruded upon us, and form other links of our unceasing catenations of
ideas.
10. The absence of the stimuli of external bodies, and of volition, in our
dreams renders the organs of sense liable to be more strongly affected by
the powers of sensation, and of association. For our desires or aversions,
or the obtrusions of surrounding bodies, dissever the sensitive and
associate tribes of ideas in our waking hours by introducing those of
irritation and volition amongst them. Hence proceeds the superior
distinctness of pleasurable or painful imagery in our sleep; for we recal
the figure and the features of a long lost friend, whom we loved, in our
dreams with much more accuracy and vivacity than in our waking thoughts.
This circumstance contributes to prove, that our ideas of imagination are
reiterations of those motions of our organs of sense, which were excited by
external objects; because while we are exposed to the stimuli of present
objects, our ideas of absent objects cannot be so distinctly formed.
11. The rapidity of the succession of transactions in our dreams is almost
inconceivable; insomuch that, when we are accidentally awakened by the
jarring of a door, which is opened into our bed-chamber, we sometimes dream
a whole history of thieves or fire in the very instant of awaking.
During the suspension of volition we cannot compare our other ideas with
those of the parts of time in which they exist; that is, we cannot compare
the imaginary scene, which is before us, with those changes of it, which
precede or follow it: because this act of comparing requires recollection
or voluntary exertion. Whereas in our waking hours, we are perpetually
making this comparison, and by that means our waking ideas are kept
confident with each other by intuitive analogy; but this companion retards
the succession of them, by occasioning their repetition. Add to this, that
the transactions of our dreams consist chiefly of visible ideas, and that a
whole history of thieves and fire may be _beheld_ in an instant of time
like the figures in a picture.
12. From this incapacity of attending to the parts of time in our dreams,
arises our ignorance of the length of the night; which, but from our
constant experience to the contrary, we should conclude was but a few
minutes, when our sleep is perfect. The same happens in our reveries; thus
when we are possessed with vehement joy, grief, or anger, time appears
short, for we exert no volition to compare the present scenery with the
past or future; but when we are compelled to perform those exercises of
mind or body, which, are unmixed with passion, as in travelling over a
dreary country, time appears long; for our desire to finish our journey
occasions us more frequently to compare our present situation with the
parts of time or place, which are before and behind us.
So when we are enveloped in deep contemplation of any kind, or in reverie,
as in reading a very interesting play or romance, we measure time very
inaccurately; and hence, if a play greatly affects our passions, the
absurdities of passing over many days or years, and or perpetual changes of
place, are not perceived by the audience; as is experienced by every one,
who reads or sees some plays of the immortal Shakespear; but it is
necessary for inferior authors to observe those rules of the [Greek:
pithanon] and [Greek: prepon] inculcated by Aristotle, because their works
do not interest the passions sufficiently to produce complete reverie.
Those works, however, whether a romance or a sermon, which do not interest
us so much as to induce reverie, may nevertheless incline us to sleep. For
those pleasurable ideas, which are presented to us, and are too gentle to
excite laughter, (which is attended with interrupted voluntary exertions,
as explained Sect. XXXIV. 1. 4.) and which are not accompanied with any
other emotion, which usually excites some voluntary exertion, as anger, or
fear, are liable to produce sleep; which consists in a suspension of all
voluntary power. But if the ideas thus presented to us, and interest our
attention, are accompanied with so much pleasurable or painful sensation as
to excite our voluntary exertion at the same time, reverie is the
consequence. Hence an interesting play produces reverie, a tedious one
produces sleep: in the latter we become exhausted by attention, and are not
excited to any voluntary exertion, and therefore sleep; in the former we
are excited by some emotion, which prevents by its pain the suspension of
volition, and in as much as it interests us, induces reverie, as explained
in the next Section.
But when our sleep is imperfect, as when we have determined to rise in half
an hour, time appears longer to us than in most other situations. Here our
solicitude not to oversleep the determined time induces us in this
imperfect sleep to compare the quick changes of imagined scenery with the
parts of time or place, they would have taken up, had they real exigence;
and that more frequently than in our waking hours; and hence the time
appears longer to us: and I make no doubt, but the permitted time appears
long to a man going to the gallows, as the fear of its quick lapse will
make him think frequently about it.
13. As we gain our knowledge of time by comparing the present scenery with
the past and future, and of place by comparing the situations of objects
with each other; so we gain our idea of consciousness by comparing
ourselves with the scenery around us; and of identity by comparing our
present consciousness with our past consciousness: as we never think of
time or place, but when we make the companions above mentioned, so we never
think of consciousness, but when we compare our own existence with that of
other objects; nor of identity, but when we compare our present and our
past consciousness. Hence the consciousness of our own existence, and of
our identity, is owing to a voluntary exertion of our minds: and on that
account in our complete dreams we neither measure time, are surprised at
the sudden changes of place, nor attend to our own existence, or identity;
because our power of volition is suspended. But all these circumstances are
more or less observable in our incomplete ones; for then we attend a little
to the lapse of time, and the changes of place, and to our own existence;
and even to our identity of person; for a lady seldom dreams, that she is a
soldier; nor a man, that he is brought to bed.
14. As long as our sensations only excite their sensual motions, or ideas,
our sleep continues sound; but as soon as they excite desires or aversions,
our sleep becomes imperfect; and when that desire or aversion is so strong,
as to produce voluntary motions, we begin to awake; the larger muscles of
the body are brought into action to remove that irritation or sensation,
which a continued posture has caused; we stretch our limbs, and yawn, and
our sleep is thus broken by the accumulation of voluntary power.
Sometimes it happens, that the act of waking is suddenly produced, and this
soon after the commencement of sleep; which is occasioned by some sensation
so disagreeable, as instantaneously to excite the power of volition; and a
temporary action of all the voluntary motions suddenly succeeds, and we
start awake. This is sometimes accompanied with loud noise in the ears, and
with some degree of fear; and when it is in great excess, so as to produce
continued convulsive motions of those muscles, which are generally
subservient to volition, it becomes epilepsy: the fits of which in some
patients generally commence during sleep. This differs from the night-mare
described in No. 3. of this Section, because in that the disagreeable
sensation is not so great as to excite the power of volition into action;
for as soon as that happens, the disease ceases.
Another circumstance, which sometimes awakes people soon after the
commencement of their sleep, is where the voluntary power is already so
great in quantity as almost to prevent them from falling asleep, and then a
little accumulation of it soon again awakens them; this happens in cases of
insanity, or where the mind has been lately much agitated by fear or anger.
There is another circumstance in which sleep is likewise of short duration,
which arises from great debility, as after great over-fatigue, and in some
fevers, where the strength of the patient is greatly diminished, as in
these cases the pulse intermits or flutters, and the respiration is
previously affected, it seems to originate from the want of some voluntary
efforts to facilitate respiration, as when we are awake. And is further
treated of in Vol. II. Class I. 2. 1. 2. on the Diseases of the Voluntary
Power. Art. Somnus interruptus.
15. We come now to those motions which depend on irritation. The motions of
the arterial and glandular systems continue in our sleep, proceeding slower
indeed, but stronger and more uniformly, than in our waking hours, when
they are incommoded by external stimuli, or by the movements of volition;
the motions of the muscles subservient to respiration continue to be
stimulated into action, and the other internal senses of hunger, thirst,
and lust, are not only occasionally excited in our sleep, but their
irritative motions are succeeded by their usual sensations, and make a part
of the farrago of our dreams. These sensations of the want of air, of
hunger, thirst, and lust, in our dreams, contribute to prove, that the
nerves of the external senses are also alive and excitable in our sleep;
but as the stimuli of external objects are either excluded from them by the
darkness and silence of the night, or their access to them is prevented by
the suspension of volition, these nerves of sense fall more readily into
their connexions with sensation and with association; because much
sensorial power, which during the day was expended in moving the external
organs of sense in consequence of irritation from external stimuli, or in
consequence of volition, becomes now in some degree accumulated, and
renders the internal or immediate organs of sense more easily excitable by
the other sensorial powers. Thus in respect to the eye, the irritation from
external stimuli, and the power of volition during our waking hours,
elevate the eye-lids, adapt the aperture of the iris to the quantity of
light, the focus of the crystalline humour, and the angle of the optic
axises to the distance of the object, all which perpetual activity during
the day expends much sensorial power, which is saved during our sleep.
Hence it appears, that not only those parts of the system, which are always
excited by internal stimuli, as the stomach, intestinal canal, bile-ducts,
and the various glands, but the organs of sense also may be more violently
excited into action by the irritation from internal stimuli, or by
sensation, during our sleep than in our waking hours; because during the
suspension of volition, there is a greater quantity of the spirit of
animation to be expended by the other sensorial powers. On this account our
irritability to internal stimuli, and our sensibility to pain or pleasure,
is not only greater in sleep, but increases as our sleep is prolonged.
Whence digestion and secretion are performed better in sleep, than in our
waking hours, and our dreams in the morning have greater variety and
vivacity, as our sensibility increases, than at night when we first lie
down. And hence epileptic fits, which are always occasioned by some
disagreeable sensation, so frequently attack those, who are subject to
them, in their sleep; because at this time the system is more excitable by
painful sensation in consequence of internal stimuli; and the power of
volition is then suddenly exerted to relieve this pain, as explained Sect.
XXXIV. 1. 4.
There is a disease, which frequently affects children in the cradle, which
is termed ecstasy, and seems to consist in certain exertions to relieve
painful sensation, in which the voluntary power is not so far excited as
totally to awaken them, and yet is sufficient to remove the disagreeable
sensation, which excites it; in this case changing the posture of the child
frequently relieves it.
I have at this time under my care an elegant young man about twenty-two
years of age, who seldom sleeps more than an hour without experiencing a
convulsion fit; which ceases in about half a minute without any subsequent
stupor. Large doses of opium only prevented the paroxysms, so long as they
prevented him from sleeping by the intoxication, which they induced. Other
medicines had no effect on him. He was gently awakened every half hour for
one night, but without good effect, as he soon slept again, and the fit
returned at about the same periods of time, for the accumulated sensorial
power, which occasioned the increased sensibility to pain, was not thus
exhausted. This case evinces, that the sensibility of the system to
internal excitation increases, as our sleep is prolonged; till the pain
thus occasioned produces voluntary exertion; which, when it is in its usual
degree, only awakens us; but when it is more violent, it occasions
convulsions.
The cramp in the calf of the leg is another kind of convulsion, which
generally commences in sleep, occasioned by the continual increase of
irritability from internal stimuli, or of sensibility, during that state of
our existence. The cramp is a violent exertion to relieve pain, generally
either of the skin from cold, or of the bowels, as in some diarrhoeas, or
from the muscles having been previously overstretched, as in walking up or
down steep hills. But in these convulsions of the muscles, which form the
calf of the leg, the contraction is so violent as to occasion another pain
in consequence of their own too violent contraction; as soon as the
original pain, which caused the contraction, is removed. And hence the
cramp, or spasm, of these muscles is continued without intermission by this
new pain, unlike the alternate convulsions and remissions in epileptic
fits. The reason, that the contraction of these muscles of the calf of the
leg is more violent during their convulsion than that of others, depends on
the weakness of their antagonist muscles; for after these have been
contracted in their usual action, as at every step in walking, they are
again extended, not, as most other muscles are, by their antagonists, but
by the weight of the whole body on the balls of the toes; and that weight
applied to great mechanical advantage on the heel, that is, on the other
end of the bone of the foot, which thus acts as a lever.
Another disease, the periods of which generally commence during our sleep,
is the asthma. Whatever may be the remote cause of paroxysms of asthma, the
immediate cause of the convulsive respiration, whether in the common
asthma, or in what is termed the convulsive asthma, which are perhaps only
different degrees of the same disease, must be owing to violent voluntary
exertions to relieve pain, as in other convulsions; and the increase of
irritability to internal stimuli, or of sensibility, during sleep must
occasion them to commence at this time.
Debilitated people, who have been unfortunately accustomed to great
ingurgitation of spirituous potation, frequently part with a great quantity
of water during the night, but with not more than usual in the day-time.
This is owing to a beginning torpor of the absorbent system, and precedes
anasarca, which commences in the day, but is cured in the night by the
increase of the irritability of the absorbent system during sleep, which
thus imbibes from the cellular membrane the fluids, which had been
accumulated there during the day; though it is possible the horizontal
position of the body may contribute something to this purpose, and also the
greater irritability of some branches of the absorbent vessels, which open
their mouths in the cells of the cellular membrane, than that of other
branches.
As soon as a person begins to sleep, the irritability and sensibility of
the system begins to increase, owing to the suspension of volition and the
exclusion of external stimuli. Hence the actions of the vessels in
obedience to internal stimulation become stronger and more energetic,
though less frequent in respect to number. And as many of the secretions
are increased, so the heat of the system is gradually increased, and the
extremities of feeble people, which had been cold during the day, become
warm. Till towards morning many people become so warm, as to find it
necessary to throw off some of their bed-clothes, as soon as they awake;
and in others sweats are so liable to occur towards morning during their
sleep.
Thus those, who are not accustomed to sleep in the open air, are very
liable to take cold, if they happen to fall asleep on a garden bench, or in
a carriage with the window open. For as the system is warmer during sleep,
as above explained, if a current of cold air affects any part of the body,
a torpor of that part is more effectually produced, as when a cold blast of
air through a key-hole or casement falls upon a person in a warm room. In
those cases the affected part possesses less irritability in respect to
heat, from its having previously been exposed to a greater stimulus of
heat, as in the warm room, or during sleep; and hence, when the stimulus of
heat is diminished, a torpor is liable to ensue; that is, we take cold.
Hence people who sleep in the open air, generally feel chilly both at the
approach of sleep, and on their awaking; and hence many people are
perpetually subject to catarrhs if they sleep in a less warm head-dress,
than that which they wear in the day.
16. Not only the sensorial powers of irritation and of sensation, but that
of association also appear to act with greater vigour during the suspension
of volition in sleep. It will be shewn in another place, that the gout
generally first attacks the liver, and that afterwards an inflammation of
the ball of the great toe commences by association, and that of the liver
ceases. Now as this change or metastasis of the activity of the system
generally commences in sleep, it follows, that these associations of motion
exist with greater energy at that time; that is, that the sensorial faculty
of association, like those of irritation and of sensation, becomes in some
measure accumulated during the suspension of volition.
Other associate tribes and trains of motions, as well as the irritative and
sensitive ones, appear to be increased in their activity during the
suspension of volition in sleep. As those which contribute to circulate the
blood, and to perform the various secretions; as well as the associate
tribes and trains of ideas, which contribute to furnish the perpetual
dreams of our dreaming imaginations.
In sleep the secretions have generally been supposed to be diminished, as
the expectorated mucus in coughs, the fluids discharged in diarrhoeas, and
in salivation, except indeed the secretion of sweat, which is often visibly
increased. This error seems to have arisen from attention to the excretions
rather than to the secretions. For the secretions, except that of sweat,
are generally received into reservoirs, as the urine into the bladder, and
the mucus of the intestines and lungs into their respective cavities; but
these reservoirs do not exclude these fluids immediately by their stimulus,
but require at the same time some voluntary efforts, and therefore permit
them to remain during sleep. And as they thus continue longer in those
receptacles in our sleeping hours, a greater part is absorbed from them,
and the remainder becomes thicker, and sometimes in less quantity, though
at the time it was secreted the fluid was in greater quantity than in our
waking hours. Thus the urine is higher coloured after long sleep; which
shews that a greater quantity has been secreted, and that more of the
aqueous and saline part has been reabsorbed, and the earthy part left in
the bladder; hence thick urine in fevers shews only a greater action of the
vessels which secrete it in the kidneys, and of those which absorb it from
the bladder.
The same happens to the mucus expectorated in coughs, which is thus
thickened by absorption of its aqueous and saline parts; and the same of
the feces of the intestines. From hence it appears, and from what has been
said in No. 15. of this Section concerning the increase of irritability and
of sensibility during sleep, that the secretions are in general rather
increased than diminished during these hours of our existence; and it is
probable that nutrition is almost entirely performed in sleep; and that
young animals grow more at this time than in their waking hours, as young
plants have long since been observed to grow more in the night, which is
their time of sleep.
17. Two other remarkable circumstances of our dreaming ideas are their
inconsistency, and the total absence of surprise. Thus we seem to be
present at more extraordinary metamorphoses of animals or trees, than are
to be met with in the fables of antiquity; and appear to be transported
from place to place, which seas divide, as quickly as the changes of
scenery are performed in a play-house; and yet are not sensible of their
inconsistency, nor in the least degree affected with surprise.
We must consider this circumstance more minutely. In our waking trains of
ideas, those that are inconsistent with the usual order of nature, so
rarely have occurred to us, that their connexion is the slightest of all
others: hence, when a consistent train of ideas is exhausted, we attend to
the external stimuli, that usually surround us, rather than to any
inconsistent idea, which might otherwise present itself; and if an
inconsistent idea should intrude itself, we immediately compare it with the
preceding one, and voluntarily reject the train it would introduce; this
appears further in the Section on Reverie, in which state of the mind
external stimuli are not attended to, and yet the streams of ideas are kept
consistent by the efforts of volition. But as our faculty of volition is
suspended, and all external stimuli are excluded in sleep, this slighter
connexion of ideas takes place; and the train is said to be inconsistent;
that is, dissimilar to the usual order of nature.
But, when any consistent train of sensitive or voluntary ideas is flowing
along, if any external stimulus affects us so violently, as to intrude
irritative ideas forcibly into the mind, it disunites the former train of
ideas, and we are affected with surprise. These stimuli of unusual energy
or novelty not only disunite our common trains of ideas, but the trains of
muscular motions also, which have not been long established by habit, and
disturb those that have. Some people become motionless by great surprise,
the fits of hiccup and or ague have been often removed by it, and it even
affects the movements of the heart, and arteries; but in our sleep, all
external stimuli are excluded, and in consequence no surprise can exist.
See Section XVII. 3. 7.
18. We frequently awake with pleasure from a dream, which has delighted us,
without being able to recollect the transactions of it; unless perhaps at a
distance of time, some analogous idea may introduce afresh this forgotten
train: and in our waking reveries we sometimes in a moment lose the train
of thought, but continue to feel the glow of pleasure, or the depression of
spirits, it occasioned: whilst at other times we can retrace with ease
these histories of our reveries and dreams.
The above explanation of surprise throws light upon this subject. When we
are suddenly awaked by any violent stimulus, the surprise totally disunites
the trains of our sleeping ideas from these of our waking ones; but if we
gradually awake, this does not happen; and we readily unravel the preceding
trains of imagination.
19. There are various degrees of surprise; the more intent we are upon the
train of ideas, which we are employed about, the more violent must be the
stimulus that interrupts them, and the greater is the degree of surprise. I
have observed dogs, who have slept by the fire, and by their obscure
barking and struggling have appeared very intent on their prey, that shewed
great surprise for a few seconds after their awaking by looking eagerly
around them; which they did not do at other times of waking. And an
intelligent friend of mine has remarked, that his lady, who frequently
speaks much and articulately in her sleep, could never recollect her dreams
in the morning, when this happened to her: but that when she did not speak
in her sleep, she could always recollect them.
Hence, when our sensations act so strongly in sleep as to influence the
larger muscles, as in those, who talk or struggle in their dreams; or in
those, who are affected with complete reverie (as described in the next
Section), great surprise is produced, when they awake; and these as well as
those, who are completely drunk or delirious, totally forget afterwards
their imaginations at those times.
20. As the immediate cause of sleep consists in the suspension of volition,
it follows, that whatever diminishes the general quantity of sensorial
power, or derives it from the faculty of volition, will constitute a remote
cause of sleep; such as fatigue from muscular or mental exertion, which
diminishes the general quantity of sensorial power; or an increase of the
sensitive motions, as by attending to soft music, which diverts the
sensorial power from the faculty of volition; or lastly, by increase of the
irritative motions, as by wine, or food; or warmth; which not only by their
expenditure of sensorial power diminish the quantity of volition; but also
by their producing pleasureable sensations (which occasion other muscular
or sensual motions in consequence), doubly decrease the voluntary power,
and thus more forcibly produce sleep. See Sect. XXXIV. 1. 4.
Another method of inducing sleep is delivered in a very ingenious work
lately published by Dr. Beddoes. Who, after lamenting that opium frequently
occasions restlessness, thinks, "that in most cases it would be better to
induce sleep by the abstraction of stimuli, than by exhausting the
excitability;" and adds, "upon this principle we could not have a better
soporific than an atmosphere with a diminished proportion of oxygene air,
and that common air might be admitted after the patient was asleep."
(Observ. on Calculus, &c. by Dr. Beddoes, Murray.) If it should be found to
be true, that the excitability of the system depends on the quantity of
oxygene absorbed by the lungs in respiration according to the theory of Dr.
Beddoes, and of M. Girtanner, this idea of sleeping in an atmosphere with
less oxygene in its composition might be of great service in epileptic
cases, and in cramp, and even in fits of the asthma, where their periods
commence from the increase of irritability during sleep.
Sleep is likewise said to be induced by mechanic pressure on the brain in
the cases of spina bifida. Where there has been a defect of one of the
vertebræ of the back, a tumour is protruded in consequence; and, whenever
this tumour has been compressed by the hand, sleep is said to be induced,
because the whole of the brain both within the head and spine becomes
compressed by the retrocession of the fluid within the tumour. But by what
means a compression of the brain induces sleep has not been explained, but
probably by diminishing the secretion of sensorial power, and then the
voluntary motions become suspended previously to the irritative ones, as
occurs in most dying persons.
Another way of procuring sleep mechanically was related to me by Mr.
Brindley, the famous canal engineer, who was brought up to the business of
a mill-wright; he told me, that he had more than once seen the experiment
of a man extending himself across the large stone of a corn-mill, and that
by gradually letting the stone whirl, the man fell asleep, before the stone
had gained its full velocity, and he supposed would have died without pain
by the continuance or increase of the motion. In this case the centrifugal
motion of the head and feet must accumulate the blood in both those
extremities of the body, and thus compress the brain.
Lastly, we should mention the application of cold; which, when in a less
degree, produces watchfulness by the pain it occasions, and the tremulous
convulsions of the subcutaneous muscles; but when it is applied in great
degree, is said to produce sleep. To explain this effect it has been said,
that as the vessels of the skin and extremities become first torpid by the
want of the stimulus of heat, and as thence less blood is circulated
through them, as appears from their paleness, a greater quantity of blood
poured upon the brain produces sleep by its compression of that organ. But
I should rather imagine, that the sensorial power becomes exhausted by the
convulsive actions in consequence of the pain of cold, and of the voluntary
exercise previously used to prevent it, and that the sleep is only the
beginning to die, as the suspension of voluntary power in lingering deaths
precedes for many hours the extinction of the irritative motions.
21. The following are the characteristic circumstances attending perfect
sleep.
1. The power of volition is totally suspended.
2. The trains of ideas caused by sensation proceed with greater facility
and vivacity; but become inconsistent with the usual order of nature. The
muscular motions caused by sensation continue; as those concerned in our
evacuations during infancy, and afterwards in digestion, and in priapismus.
3. The irritative muscular motions continue, as those concerned in the
circulation, in secretion, in respiration. But the irritative sensual
motions, or ideas, are not excited; as the immediate organs of sense are
not stimulated into action by external objects, which are excluded by the
external organs of sense; which are not in sleep adapted to their reception
by the power of volition, as in our waking hours.
4. The associate motions continue; but their first link is not excited into
action by volition, or by external stimuli. In all respects, except those
above mentioned, the three last sensorial powers are somewhat increased in
energy during the suspension of volition, owing to the consequent
accumulation of the spirit of animation.
* * * * *
SECT. XIX.
OF REVERIE.
1. _Various degrees of reverie._ 2. _Sleep-walkers. Case of a young
lady. Great surprise at awaking. And total forgetfulness of what passed
in reverie._ 3. _No suspension of volition in reverie._ 4. _Sensitive
motions continue, and are consistent._ 5. _Irritative motions continue,
but are not succeeded by sensation._ 6. _Volition necessary for the
perception of feeble impressions._ 7. _Associated motions continue._ 8.
_Nerves of sense are irritable in sleep, but not in reverie._ 9.
_Somnambuli are not asleep. Contagion received but once._ 10.
_Definition of reverie._
1. When we are employed with great sensation of pleasure, or with great
efforts of volition, in the pursuit of some interesting train of ideas, we
cease to be conscious of our existence, are inattentive to time and place,
and do not distinguish this train of sensitive and voluntary ideas from the
irritative ones excited by the presence of external objects, though our
organs of sense are furnished with their accustomed stimuli, till at length
this interesting train of ideas becomes exhausted, or the appulses of
external objects are applied with unusual violence, and we return with
surprise, or with regret, into the common track of life. This is termed
reverie or studium.
In some constitutions these reveries continue a considerable time, and are
not to be removed without greater difficulty, but are experienced in a less
degree by us all; when we attend earnestly to the ideas excited by volition
or sensation, with their associated connexions, but are at the same time
conscious at intervals of the stimuli of surrounding bodies. Thus in being
present at a play, or in reading a romance, some persons are so totally
absorbed as to forget their usual time of sleep, and to neglect their
meals; while others are said to have been so involved in voluntary study as
not to have heard the discharge of artillery; and there is a story of an
Italian politician, who could think so intensely on other subjects, as to
be insensible to the torture of the rack.
From hence it appears, that these catenations of ideas and muscular
motions, which form the trains of reverie, are composed both of voluntary
and sensitive associations of them; and that these ideas differ from those
of delirium or of sleep, as they are kept consistent by the power of
volition; and they differ also from the trains of ideas belonging to
insanity, as they are as frequently excited by sensation as by volition.
But lastly, that the whole sensorial power is so employed on these trains
of complete reverie, that like the violent efforts of volition, as in
convulsions or insanity; or like the great activity of the irritative
motions in drunkenness; or of the sensitive motions in delirium; they
preclude all sensation consequent to external stimulus.
2. Those persons, who are said to walk in their sleep, are affected with
reverie to so great a degree, that it becomes a formidable disease; the
essence of which consists in the inaptitude of the mind to attend to
external stimuli. Many histories of this disease have been published by
medical writers; of which there is a very curious one in the Lausanne
Transactions. I shall here subjoin an account of such a case, with its
cure, for the better illustration of this subject.
A very ingenious and elegant young lady, with light eyes and hair, about
the age of seventeen, in other respects well, was suddenly seized soon
after her usual menstruation with this very wonderful malady. The disease
began with vehement convulsions of almost every muscle of her body, with
great but vain efforts to vomit, and the most violent hiccoughs, that can
be conceived: these were succeeded in about an hour with a fixed spasm; in
which one hand was applied to her head, and the other to support it: in
about half an hour these ceased, and the reverie began suddenly, and was at
first manifest by the look of her eyes and countenance, which seemed to
express attention. Then she conversed aloud with imaginary persons with her
eyes open, and could not for about an hour be brought to attend to the
stimulus of external objects by any kind of violence, which it was proper
to use; these symptoms returned in this order every day for five or six
weeks.
These conversations were quite consistent, and we could understand, what
she supposed her imaginary companions to answer, by the continuation of her
part of the discourse. Sometimes she was angry, at other times shewed much
wit and vivacity, but was most frequently inclined to melancholy. In these
reveries she sometimes sung over some music with accuracy, and repeated
whole pages from the English poets. In repeating some lines from Mr. Pope's
works she had forgot one word, and began again, endeavouring to recollect
it; when she came to the forgotten word, it was shouted aloud in her ear,
and this repeatedly, to no purpose; but by many trials she at length
regained it herself.
These paroxysms were terminated with the appearance of inexpressible
surprise, and great fear, from which she was some minutes in recovering
herself, calling on her sister with great agitation, and very frequently
underwent a repetition of convulsions, apparently from the pain of fear.
See Sect. XVII. 3. 7.
After having thus returned for about an hour every day for two or three
weeks, the reveries seemed to become less complete, and some of their
circumstances varied; so that she could walk about the room in them without
running against any of the furniture; though these motions were at first
very unsteady and tottering. And afterwards she once drank a dish of tea,
when the whole apparatus of the tea-table was set before her; and expressed
some suspicion, that a medicine was put into it, and once seemed to smell
of a tuberose, which was in flower in her chamber, and deliberated aloud
about breaking it from the stem, saying, "it would make her sister so
charmingly angry." At another time in her melancholy moments she heard the
sound of a passing bell, "I wish I was dead," she cried, listening to the
bell, and then taking off one of her shoes, as she sat upon the bed, "I
love the colour black," says she, "a little wider, and a little longer,
even this might make me a coffin!"--Yet it is evident, she was not sensible
at this time, any more than formerly, of seeing or hearing any person about
her; indeed when great light was thrown upon her by opening the shutters of
the window, her trains of ideas seemed less melancholy; and when I have
forcibly held her hands, or covered her eyes, she appeared to grow
impatient, and would say, she could not tell what to do, for she could
neither see nor move. In all these circumstances her pulse continued
unaffected as in health. And when the paroxysm was over, she could never
recollect a single idea of what had passed in it.
This astonishing disease, after the use of many other medicines and
applications in vain, was cured by very large doses of opium given about an
hour before the expected returns of the paroxysms; and after a few
relapses, at the intervals of three or four months, entirely disappeared.
But she continued at times to have other symptoms of epilepsy.
3. We shall only here consider, what happened during the time of her
reveries, as that is our present subject; the fits of convulsion belong to
another part of this treatise. Sect. XXXIV. 1. 4.
There seems to have been no suspension of volition during the fits of
reverie, because she endeavoured to regain the lost idea in repeating the
lines of poetry, and deliberated about breaking the tuberose, and suspected
the tea to have been medicated.
4. The ideas and muscular movements depending on sensation were exerted
with their usual vivacity, and were kept from being inconsistent by the
power of volition, as appeared from her whole conversation, and was
explained in Sect. XVII. 3. 7. and XVIII. 16.
5. The ideas and motions dependant on irritation during the first weeks of
her disease, whilst the reverie was complete, were never succeeded by the
sensation of pleasure or pain; as she neither saw, heard, nor felt any of
the surrounding objects. Nor was it certain that any irritative motions
succeeded the stimulus of external objects, till the reverie became less
complete, and then she could walk about the room without running against
the furniture of it. Afterwards, when the reverie became still less
complete from the use of opium, some few irritations were at times
succeeded by her attention to them. As when she smelt at a tuberose, and
drank a dish of tea, but this only when she seemed voluntarily to attend to
them.
6. In common life when we listen to distant sounds, or wish to distinguish
objects in the night, we are obliged strongly to exert our volition to
dispose the organs of sense to perceive them, and to suppress the other
trains of ideas, which might interrupt these feeble sensations. Hence in
the present history the strongest stimuli were not perceived, except when
the faculty of volition was exerted on the organ of sense; and then even
common stimuli were sometimes perceived: for her mind was so strenuously
employed in pursuing its own trains of voluntary or sensitive ideas, that
no common stimuli could so far excite her attention as to disunite them;
that is, the quantity of volition or of sensation already existing was
greater than any, which could be produced in consequence of common degrees
of stimulation. But the few stimuli of the tuberose, and of the tea, which
she did perceive, were such, as accidentally coincided with the trains of
thought, which were passing in her mind; and hence did not disunite those
trains, and create surprise. And their being perceived at all was owing to
the power of volition preceding or coinciding with that of irritation.
This explication is countenanced by a fact mentioned concerning a
somnambulist in the Lausanne Transactions, who sometimes opened his eyes
for a short time to examine, where he was, or where his ink-pot stood, and
then shut them again, dipping his pen into the pot every now and then, and
writing on, but never opening his eyes afterwards, although he wrote on
from line to line regularly, and corrected some errors of the pen, or in
spelling: so much easier was it to him to refer to his ideas of the
positions of things, than to his perceptions of them.
7. The associated motions persisted in their usual channel, as appeared by
the combinations of her ideas, and the use of her muscles, and the equality
of her pulse; for the natural motions of the arterial system, though
originally excited like other motions by stimulus, seem in part to continue
by their association with each other. As the heart of a viper pulsates long
after it is cut out of the body, and removed from the stimulus of the
blood.
8. In the section on sleep, it was observed that the nerves of sense are
equally alive and susceptible to irritation in that state, as when we are
awake; but that they are secluded from stimulating objects, or rendered
unfit to receive them: but in complete reverie the reverse happens, the
immediate organs of sense are exposed to their usual stimuli; but are
either not excited into action at all, or not into so great action, as to
produce attention or sensation.
The total forgetfulness of what passes in reveries; and the surprise on
recovering from them, are explained in Section XVIII. 19. and in Section
XVII. 3. 7.
9. It appears from hence, that reverie is a disease of the epileptic or
cataleptic kind, since the paroxysms of this young lady always began and
frequently terminated with convulsions; and though in its greatest degree
it has been called somnambulation, or sleep-walking, it is totally
different from sleep; because the essential character of sleep consists in
the total suspension of volition, which in reverie is not affected; and the
essential character of reverie consists not in the absence of those
irritative motions of our senses, which are occasioned by the stimulus of
external objects, but in their never being productive of sensation. So that
during a fit of reverie that strange event happens to the whole system of
nerves, which occurs only to some particular branches of them in those, who
are a second time exposed to the action of contagious matter. If the matter
of the small-pox be inserted into the arm of one, who has previously had
that disease, it will stimulate the wound, but the general sensation or
inflammation of the system does not follow, which constitutes the disease.
See Sect. XII. 3. 6. XXXIII. 2. 8.
10. The following is the definition or character of complete reverie. 1.
The irritative motions occasioned by internal stimuli continue, those from
the stimuli of external objects are either not produced at all, or are
never succeeded by sensation or attention, unless they are at the same time
excited by volition. 2. The sensitive motions continue, and are kept
consistent by the power of volition. 3. The voluntary motions continue
undisturbed. 4. The associate motions continue undisturbed.
Two other cases of reverie are related in Section XXXIV. 3. which further
evince, that reverie is an effort of the mind to relieve some painful
sensation, and is hence allied to convulsion, and to insanity. Another case
is related in Class III. 1. 2. 2.
* * * * *
SECT. XX.
OF VERTIGO.
1. _We determine our perpendicularity by the apparent motions of
objects. A person hood-winked cannot walk in a straight line. Dizziness
in looking from a tower, in a room stained with uniform lozenges, on
riding over snow._ 2. _Dizziness from moving objects. A whirling-wheel.
Fluctuations of a river. Experiment with a child._ 3. _Dizziness from
our own motions and those of other objects._ 4. _Riding over a broad
stream. Sea-sickness._ 5. _Of turning round on one foot. Dervises in
Turkey. Attention of the mind prevents slight sea-sickness. After a
voyage ideas of vibratory motions are still perceived on shore._ 6.
_Ideas continue some time after they are excited. Circumstances of
turning on one foot, standing on a tower, and walking in the dark,
explained._ 7. _Irritative ideas of apparent motions. Irritative ideas
of sounds. Battèment of the sound of bells and organ-pipes. Vertiginous
noise in the head. Irritative motions of the stomach, intestines, and
glands._ 8. _Symptoms that accompany vertigo. Why vomiting comes on in
strokes of the palsy. By the motion of a ship. By injuries on the head.
Why motion makes sick people vomit._ 9. _Why drunken people are
vertiginous. Why a stone in the ureter, or bile-duct, produces
vomiting._ 10. _Why after a voyage ideas of vibratory motions are
perceived on shore._ 11. _Kinds of vertigo and their cure._ 12.
_Definition of vertigo._
1. In learning to walk we judge of the distances of the objects, which we
approach, by the eye; and by observing their perpendicularity determine our
own. This circumstance not having been attended to by the writers on
vision, the disease called vertigo or dizziness has been little understood.
When any person loses the power of muscular action, whether he is erect or
in a sitting posture, he sinks down upon the ground; as is seen in fainting
fits, and other instances of great debility. Hence it follows, that some
exertion of muscular power is necessary to preserve our perpendicular
attitude. This is performed by proportionally exerting the antagonist
muscles of the trunk, neck, and limbs; and if at any time in our
locomotions we find ourselves inclining to one side, we either restore our
equilibrium by the efforts of the muscles on the other side, or by moving
one of our feet extend the base, which we rest upon, to the new center of
gravity.
But the most easy and habitual manner of determining our want of
perpendicularity, is by attending to the apparent motion of the objects
within the sphere of distinct vision; for this apparent motion of objects,
when we incline from our perpendicularity, or begin to fall, is as much
greater than the real motion of the eye, as the diameter of the sphere of
distinct vision is to our perpendicular height.
Hence no one, who is hood-winked, can walk in a straight line for a hundred
steps together; for he inclines so greatly, before he is warned of his want
of perpendicularity by the sense of touch, not having the apparent motions
of ambient objects to measure this inclination by, that he is necessitated
to move one of his feet outwards, to the right or to the left, to support
the new centre of gravity, and thus errs from the line he endeavours to
proceed in.
For the same reason many people become dizzy, when they look from the
summit of a tower, which is raised much above all other objects, as these
objects are out of the sphere of distinct vision, and they are obliged to
balance their bodies by the less accurate feelings of their muscles.
There is another curious phenomenon belonging to this place, if the
circumjacent visible objects are so small, that we do not distinguish their
minute parts; or so similar, that we do not know them from each other; we
cannot determine our perpendicularity by them. Thus in a room hung with a
paper, which is coloured over with similar small black lozenges or
rhomboids, many people become dizzy; for when they begin to fall, the next
and the next lozenge succeeds upon the eye; which they mistake for the
first, and are not aware, that they have any apparent motion. But if you
fix a sheet of paper, or draw any other figure, in the midst of these
lozenges, the charm ceases, and no dizziness is perceptible.--The same
occurs, when we ride over a plain covered with snow without trees or other
eminent objects.
2. But after having compared visible objects at rest with the sense of
touch, and learnt to distinguish their shapes and shades, and to measure
our want of perpendicularity by their apparent motions, we come to consider
them in real motion. Here a new difficulty occurs, and we require some
experience to learn the peculiar mode of motion of any moving objects,
before we can make use of them for the purposes of determining our
perpendicularity. Thus some people become dizzy at the sight of a whirling
wheel, or by gazing on the fluctuations of a river, if no steady objects
are at the same time within the sphere of their distinct vision; and when a
child first can stand erect upon his legs, if you gain his attention to a
white handkerchief steadily extended like a sail, and afterwards make it
undulate, he instantly loses his perpendicularity, and tumbles on the
ground.
3. A second difficulty we have to encounter is to distinguish our own real
movements from the apparent motions of objects. Our daily practice of
walking and riding on horseback soon instructs us with accuracy to discern
these modes of motion, and to ascribe the apparent motions of the ambient
objects to ourselves; but those, which we have not acquired by repeated
habit, continue to confound us. So as we ride on horseback the trees and
cottages, which occur to us, appear at rest; we can measure their distances
with our eye, and regulate our attitude by them; yet if we carelessly
attend to distant hills or woods through a thin hedge, which is near us, we
observe the jumping and progressive motions of them; as this is increased
by the paralax of these objects; which we have not habituated ourselves to
attend to. When first an European mounts an elephant sixteen feet high, and
whose mode of motion he is not accustomed to, the objects seem to undulate,
as he passes, and he frequently becomes sick and vertiginous, as I am well
informed. Any other unusual movement of our bodies has the same effect, as
riding backwards in a coach, swinging on a rope, turning round swiftly on
one leg, scating on the ice, and a thousand others. So after a patient has
been long confined to his bed, when he first attempts to walk, he finds
himself vertiginous, and is obliged by practice to learn again the
particular modes of the apparent motions of objects, as he walks by them.
4. A third difficulty, which occurs to us in learning to balance ourselves
by the eye, is, when both ourselves and the circumjacent objects are in
real motion. Here it is necessary, that we should be habituated to both
these modes of motion in order to preserve our perpendicularity. Thus on
horseback we accurately observe another person, whom we meet, trotting
towards us, without confounding his jumping and progressive motion with our
own, because we have been accustomed to them both; that is, to undergo the
one, and to see the other at the same time. But in riding over a broad and
fluctuating stream, though we are well experienced in the motions of our
horse, we are liable to become dizzy from our inexperience in that of the
water. And when first we go on ship-board, where the movements of
ourselves, and the movements of the large waves are both new to us, the
vertigo is almost unavoidable with the terrible sickness, which attends it.
And this I have been assured has happened to several from being removed
from a large ship into a small one; and again from a small one into a man
of war.
5. From the foregoing examples it is evident, that, when we are surrounded
with unusual motions, we lose our perpendicularity: but there are some
peculiar circumstances attending this effect of moving objects, which we
come now to mention, and shall hope from the recital of them to gain some
insight into the manner of their production.
When a child moves round quick upon one foot, the circumjacent objects
become quite indistinct, as their distance increases their apparent
motions; and this great velocity confounds both their forms, and their
colours, as is seen in whirling round a many coloured wheel; he then loses
his usual method of balancing himself by vision, and begins to stagger, and
attempts to recover himself by his muscular feelings. This staggering adds
to the instability of the visible objects by giving a vibratory motion
besides their rotatory one. The child then drops upon the ground, and the
neighbouring objects seem to continue for some seconds of time to circulate
around him, and the earth under him appears to librate like a balance. In
some seconds of time these sensations of a continuation of the motion of
objects vanish; but if he continues turning round somewhat longer, before
he falls, sickness and vomiting are very liable to succeed. But none of
these circumstances affect those who have habituated themselves to this
kind of motion, as the dervises in Turkey, amongst whom these swift
gyrations are a ceremony of religion.
In an open boat passing from Leith to Kinghorn in Scotland, a sudden change
of the wind shook the undistended sail, and stopt our boat; from this
unusual movement the passengers all vomited except myself. I observed, that
the undulation of the ship, and the instability of all visible objects,
inclined me strongly to be sick; and this continued or increased, when I
closed my eyes, but as often as I bent my attention with energy on the
management and mechanism of the ropes and sails, the sickness ceased; and
recurred again, as often as I relaxed this attention; and I am assured by a
gentleman of observation and veracity, that he has more than once observed,
when the vessel has been in immediate danger, that the sea-sickness of the
passengers has instantaneously ceased, and recurred again, when the danger
was over.
Those, who have been upon the water in a boat or ship so long, that they
have acquired the necessary habits of motion upon that unstable element, at
their return on land frequently think in their reveries, or between
sleeping and waking, that they observe the room, they sit in, or some of
its furniture, to librate like the motion of the vessel. This I have
experienced myself, and have been told, that after long voyages, it is some
time before these ideas entirely vanish. The same is observable in a less
degree after having travelled some days in a stage coach, and particularly
when we lie down in bed, and compose ourselves to sleep; in this case it is
observable, that the rattling noise of the coach, as well as the undulatory
motion, haunts us. The drunken vertigo, and the vulgar custom of rocking
children, will be considered in the next Section.
6. The motions, which are produced by the power of volition, may be
immediately stopped by the exertion of the same power on the antagonist
muscles; otherwise these with all the other classes of motion continue to
go on, some time after they are excited, as the palpitation of the heart
continues after the object of fear, which occasioned it, is removed. But
this circumstance is in no class of motions more remarkable than in those
dependent on irritation; thus if any one looks at the sun, and then covers
his eyes with his hand, he will for many seconds of time, perceive the
image of the sun marked on his retina: a similar image of all other visible
objects would remain some time formed on the retina, but is extinguished by
the perpetual change of the motions of this nerve in our attention to other
objects. To this must be added, that the longer time any movements have
continued to be excited without fatigue to the organ, the longer will they
continue spontaneously, after the excitement is withdrawn: as the taste of
tobacco in the mouth after a person has been smoaking it.
This taste remains so strong, that if a person continues to draw air
through a tobacco pipe in the dark, after having been smoking some time, he
cannot distinguish whether his pipe be lighted or not.
From these two considerations it appears, that the dizziness felt in the
head, after seeing objects in unusual motion, is no other than a
continuation of the motions of the optic nerve excited by those objects and
which engage our attention. Thus on turning round on one foot, the vertigo
continues for some seconds of time after the person is fallen on the
ground; and the longer he has continued to revolve, the longer will
continue these successive motions of the parts of the optic nerve.
_Additional Observations on _VERTIGO.
After revolving with your eyes open till you become vertiginous, as
soon as you cease to revolve, not only the circum-ambient objects
appear to circulate round you in a direction contrary to that, in which
you have been turning, but you are liable to roll your eyes forwards
and backwards; as is well observed, and ingeniously demonstrated by Dr.
Wells in a late publication on vision. The same occurs, if you revolve
with your eyes closed, and open them immediately at the time of your
ceasing to turn; and even during the whole time of revolving, as may be
felt by your hand pressed lightly on your closed eyelids. To these
movements of the eyes, of which he supposes the observer to be
inconscious, Dr. Wells ascribes the apparent circumgyration of objects
on ceasing to revolve.
The cause of thus turning our eyes forwards, and then back again, after
our body is at rest, depends, I imagine, on the same circumstance,
which induces us to follow the indistinct spectra, which are formed on
one side of the center of the retina, when we observe them apparently
on clouds, as described in Sect. XL. 2. 2.; and then not being able to
gain a more distinct vision of them, we turn our eyes back, and again
and again pursue the flying shade.
But this rolling of the eyes, after revolving till we become
vertiginous, cannot cause the apparent circumgyration of objects, in a
direction contrary to that in which we have been revolving, for the
following reasons. 1. Because in pursuing a spectrum in the sky, or on
the ground, as above mentioned, we perceive no retrograde motions of
objects. 2. Because the apparent retrograde motions of objects, when we
have revolved till we are vertiginous, continues much longer than the
rolling of the eyes above described.
3. When we have revolved from right to left, the apparent motion of
objects, when we stop, is from left to right; and when we have revolved
from left to right, the apparent circulation of objects is from right
to left; yet in both these cases the eyes of the revolver are seen
equally to roll forwards and backwards.
4. Because this rolling of the eyes backwards and forwards takes place
during our revolving, as may be perceived by the hand lightly pressed
on the closed eyelids, and therefore exists before the effect ascribed
to it.
And fifthly, I now come to relate an experiment, in which the rolling
of the eyes does not take place at all after revolving, and yet the
vertigo is more distressing than in the situations above mentioned. If
any one looks steadily at a spot in the ceiling over his head, or
indeed at his own finger held up high over his head, and in that
situation turns round till he becomes giddy; and then stops, and looks
horizontally; he now finds, that the apparent rotation of objects is
from above downwards, or from below upwards; that is, that the apparent
circulation of objects is now vertical instead of horizontal, making
part of a circle round the axis of his _eye_; and this without any
rolling of his eyeballs. The reason of there being no rolling of the
eyeballs, perceived after this experiment, is, because the images of
objects are formed in rotation round the axis of the eye, and not from
one side to the other of the axis of it; so that, as the eyeball has
not power to turn in its socket round its own axis, it cannot follow
the apparent motions of these evanescent spectra, either before or
after the body is at rest. From all which arguments it is manifest,
that these apparent retrograde gyrations of objects are not caused by
the rolling of the eyeballs; first, because no apparent retrogression
of objects is observed in other rollings of the eyes: secondly, because
the apparent retrogression of objects continues many seconds after the
rolling of the eyeballs ceases. Thirdly, because the apparent
retrogression of objects is sometimes one way, and sometimes another,
yet the rolling of the eyeballs is the same. Fourthly, because the
rolling of the eyeballs exists before the apparent retrograde motions
of objects is observed; that is, before the revolving person stops. And
fifthly, because the apparent retrograde gyration of objects is
produced, when there is no rolling of the eyeballs at all.
Doctor Wells imagines, that no spectra can be gained in the eye, if a
person revolves with his eyelids closed, and thinks this a sufficient
argument against the opinion, that the apparent progression of the
spectra of light or colours in the eye can cause the apparent
retrogression of objects in the vertigo above described; but it is
certain, when any person revolves in a light room with his eyes closed,
that he nevertheless perceives differences of light both in quantity
and colour through his eyelids, as he turns round; and readily gains
spectra of those differences. And these spectra are not very different
except in vivacity from those, which he acquires, when he revolves with
unclosed eyes, since if he then revolves very rapidly the colours and
forms of surrounding objects are as it were mixed together in his eye;.
as when, the prismatic colours are painted on a wheel, they appear
white as they revolve. The truth of this is evinced by the staggering
or vertigo of men perfectly blind, when they turn round; which is not
attended with apparent circulation of objects, but is a vertiginous
disorder of the sense of touch. Blind men balance themselves by their
sense of touch; which, being less adapted for perceiving small
deviations from their perpendicular, occasions them to carry themselves
more erect in walking. This method of balancing themselves by the
direction of their pressure against the floor, becomes disordered by
the unusual mode of action in turning round, and they begin to lose
their perpendicularity, that is, they become vertiginous; but without
any apparent circular motions of visible objects.
It will appear from the following experiments, that the apparent
progression of the ocular spectra of light or colours is the cause of
the apparent retrogression of objects, after a person has revolved,
till he is vertiginous.
First, when a person turns round in a light room with his eyes open,
but closes them before he stops, he will seem to be carried forwards in
the direction he was turning for a short time after he stops. But if he
opens his eyes again, the objects before him instantly appear to move
in a retrograde direction, and he loses the sensation of being carried
forwards. The same occurs if a person revolves in a light room with his
eyes closed; when he stops, he seems to be for a time carried forwards,
if his eyes are still closed; but the instant he opens them, the
surrounding objects appear to move in retrograde gyration. From hence
it may be concluded, that it is the sensation or imagination of our
continuing to go forwards in the direction in which we were turning,
that causes the apparent retrograde circulation of objects.
Secondly, though there is an audible vertigo, as is known by the
battement, or undulations of sound in the ears, which many vertiginous
people experience; and though there is also a tangible vertigo, as when
a blind person turns round, as mentioned above; yet as this
circumgyration of objects is an hallucination or deception of the sense
of sight, we are to look for the cause of our appearing to move
forward, when we stop with our eyes closed after gyration, to some
affection of this sense. Now, thirdly, if the spectra formed in the eye
during our rotation, continue to change, when we stand still, like the
spectra described in Sect. III. 3. 6. such changes must suggest to us
the idea or sensation of our still continuing to turn round; as is the
case, when we revolve in a light room, and close our eyes before we
stop. And lastly, on opening our eyes in the situation above described,
the objects we chance to view amid these changing spectra in the eye,
must seem to move in a contrary direction; as the moon sometimes
appears to move retrograde, when swift-gliding clouds are passing
forwards so much nearer the eye of the beholder.
To make observations on faint ocular spectra requires some degree of
habit, and composure of mind, and even patience; some of those
described in Sect. XL. were found difficult to see, by many, who tried
them; now it happens, that the mind, during the confusion of vertigo,
when all the other irritative tribes of motion, as well as those of
vision, are in some degree disturbed, together with the fear of
falling, is in a very unfit state for the contemplation of such weak
sensations, as are occasioned by faint ocular spectra. Yet after
frequently revolving, both with my eyes closed, and with them open, and
attending to the spectra remaining in them, by shading the light from
my eyelids more or less with my hand, I at length ceased to have the
idea of going forward, after I stopped with my eyes closed; and saw
changing spectra in my eyes, which seemed to move, as it were, over the
field of vision; till at length, by repeated trials on sunny days, I
persuaded myself, on opening my eyes, after revolving some time, on a
shelf of gilded books in my library, that I could perceive the spectra
in my eyes move forwards over one or two of the books, like the vapours
in the air of a summer's day; and could so far undeceive myself, as to
perceive the books to stand still. After more trials I sometimes
brought myself to believe, that I saw changing spectra of lights and
shades moving in my eyes, after turning round for some time, but did
not imagine either the spectra or the objects to be in a state of
gyration. I speak, however, with diffidence of these facts, as I could
not always make the experiments succeed, when there was not a strong
light in my room, or when my eyes were not in the most proper state for
such observations.
The ingenious and learned M. Sauvage has mentioned other theories to
account for the apparent circumgyration of objects in vertiginous
people. As the retrograde motions of the particles of blood in the
optic arteries, by spasm, or by fear, as is seen in the tails of
tadpoles, and membranes between the fingers of frogs. Another cause he
thinks may be from the librations to one side, and to the other, of the
crystalline lens in the eye, by means of involuntary actions of the
muscles, which constitute the ciliary process. Both these theories lie
under the same objection as that of Dr. Wells before mentioned; namely,
that the apparent motions of objects, after the observer has revolved
for some time, should appear to vibrate this way and that; and not to
circulate uniformly in a direction contrary to that, in which the
observer had revolved.
M. Sauvage has, lastly, mentioned the theory of colours left in the
eye, which he has termed impressions on the retina. He says,
"Experience teaches us, that impressions made on the retina by a
visible object remain some seconds after the object is removed; as
appears from the circle of fire which we see, when a fire-stick is
whirled round in the dark; therefore when we are carried round our own
axis in a circle, we undergo a temporary vertigo, when we stop; because
the impressions of the circumjacent objects remain for a time
afterwards on the retina." Nosolog. Method. Clas. VIII. I. 1. We have
before observed, that the changes of these colours remaining in the
eye, evinces them to be motions of the fine terminations of the retina,
and not impressions on it; as impressions on a passive substance must
either remain, or cease intirely. See an additional note at the end of
the second volume.
Any one, who stands alone on the top of a high tower, if he has not been
accustomed to balance himself by objects placed at such distances and with
such inclinations, begins to stagger, and endeavours to recover himself by
his muscular feelings. During this time the apparent motion of objects at a
distance below him is very great, and the spectra of these apparent motions
continue a little time after he has experienced them; and he is persuaded
to incline the contrary way to counteract their effects; and either
immediately falls, or applying his hands to the building, uses his muscular
feelings to preserve his perpendicular attitude, contrary to the erroneous
persuasions of his eyes. Whilst the person, who walks in the dark,
staggers, but without dizziness; for he neither has the sensation of moving
objects to take off his attention from his muscular feelings, nor has he
the spectra of those motions continued on his retina to add to his
confusion. It happens indeed sometimes to one landing on a tower, that the
idea of his not having room to extend his base by moving one of his feet
outwards, when he begins to incline, superadds fears to his other
inconveniences; which like surprise, joy, or any great degree of sensation,
enervates him in a moment, by employing the whole sensorial power, and by
thus breaking all the associated trains and tribes of motion.
7. The irritative ideas of objects, whilst we are awake, are perpetually
present to our sense of sight; as we view the furniture of our rooms, or
the ground, we tread upon, throughout the whole day without attending to
it. And as our bodies are never at perfect rest during our waking hours,
these irritative ideas of objects are attended perpetually with irritative
ideas of their apparent motions. The ideas of apparent motions are always
irritative ideas, because we never attend to them, whether we attend to the
objects themselves, or to their real motions, or to neither. Hence the
ideas of the apparent motions of objects are a complete circle of
irritative ideas, which continue throughout the day.
Also during all our waking hours, there is a perpetual confused sound of
various bodies, as of the wind in our rooms, the fire, distant
conversations, mechanic business; this continued buzz, as we are seldom
quite motionless, changes its loudness perpetually, like the sound of a
bell; which rises and falls as long as it continues, and seems to pulsate
on the ear. This any one may experience by turning himself round near a
waterfall; or by striking a glass bell, and then moving the direction of
its mouth towards the ears, or from them, as long as its vibrations
continue. Hence this undulation of indistinct sound makes another
concomitant circle of irritative ideas, which continues throughout the day.
We hear this undulating sound, when we are perfectly at rest ourselves,
from other sonorous bodies besides bells; as from two organ-pipes, which
are nearly but not quite in unison, when they are sounded together. When a
bell is struck, the circular form is changed into an eliptic one; the
longest axis of which, as the vibrations continue, moves round the
periphery of the bell; and when either axis of this elipse is pointed
towards our ears, the sound is louder; and less when the intermediate parts
of the elipse are opposite to us. The vibrations of the two organ-pipes may
be compared to Nonius's rule; the sound is louder, when they coincide, and
less at the intermediate times. But, as the sound of bells is the most
familiar of those sounds, which have a considerable battement, the
vertiginous patients, who attend to the irritative circles of sounds above
described, generally compare it to the noise of bells.
The peristaltic motions of our stomach and intestines, and the secretions
of the various glands, are other circles of irritative motions, some of
them more or less complete, according to our abstinence or satiety.
So that the irritative ideas of the apparent motions of objects, the
irritative battements of sounds, and the movements of our bowels and glands
compose a great circle of irritative tribes of motion: and when one
considerable part of this circle of motions becomes interrupted, the whole
proceeds in confusion, as described in Section XVII. 1. 7. on Catenation of
Motions.
8. Hence a violent vertigo, from whatever cause it happens, is generally
attended with undulating noise in the head, perversions of the motions of
the stomach and duodenum, unusual excretion of bile and gastric juice, with
much pale urine, sometimes with yellowness of the skin, and a disordered
secretion of almost every gland of the body, till at length the arterial
system is affected, and fever succeeds.
Thus bilious vomitings accompany the vertigo occasioned by the motion of a
ship; and when the brain is rendered vertiginous by a paralytic affection
of any part of the body, a vomiting generally ensues, and a great discharge
of bile: and hence great injuries of the head from external violence are
succeeded with bilious vomitings, and sometimes with abscesses of the
liver. And hence, when a patient is inclined to vomit from other causes, as
in some fevers, any motions of the attendants in his room, or of himself
when he is raised or turned in his bed, presently induces the vomiting by
superadding a degree of vertigo.
9. And conversely it is very usual with those, whose stomachs are affected
from internal causes, to be afflicted with vertigo, and noise in the head;
such is the vertigo of drunken people, which continues, when their eyes are
closed, and themselves in a recumbent posture, as well as when they are in
an erect posture, and have their eyes open. And thus the irritation of a
stone in the bile-duct, or in the ureter, or an inflammation of any of the
intestines, are accompanied with vomitings and vertigo.
In these cases the irritative motions of the stomach, which are in general
not attended to, become so changed by some unnatural stimulus, as to become
uneasy, and excite our sensation or attention. And thus the other
irritative trains of motions, which are associated with it, become
disordered by their sympathy. The same happens, when a piece of gravel
sticks in the ureter, or when some part of the intestinal canal becomes
inflamed. In these cases the irritative muscular motions are first
disturbed by unusual stimulus, and a disordered action of the sensual
motions, or dizziness ensues. While in sea-sickness the irritative sensual
motions, as vertigo, precedes; and the disordered irritative muscular
motions, as those of the stomach in vomiting, follow.
10. When these irritative motions are disturbed, if the degree be not very
great, the exertion of voluntary attention to any other object, or any
sudden sensation, will disjoin these new habits of motion. Thus some
drunken people have become sober immediately, when any accident has
strongly excited their attention; and sea-sickness has vanished, when the
ship has been in danger. Hence when our attention to other objects is most
relaxed, as just before we fall asleep, or between our reveries when awake,
these irritative ideas of motion and sound are most liable to be perceived;
as those, who have been at sea, or have travelled long in a coach, seem to
perceive the vibrations of the ship, or the rattling of the wheels, at
these intervals; which cease again, as soon as they exert their attention.
That is, at those intervals they attend to the apparent motions, and to the
battement of sounds of the bodies around them, and for a moment mistake
them for those real motions of the ship, and noise of wheels, which they
had lately been accustomed to: or at these intervals of reverie, or on the
approach of sleep, these supposed motions or sounds may be produced
entirely by imagination.
We may conclude from this account of vertigo, that sea-sickness is not an
effort of nature to relieve herself, but a necessary consequence of the
associations or catenations of animal motions. And may thence infer, that
the vomiting, which attends the gravel in the ureter, inflammations of the
bowels, and the commencement of some fevers, has a similar origin, and is
not always an effort of the vis medicatrix naturæ. But where the action of
the organ is the immediate consequence of the stimulating cause, it is
frequently exerted to dislodge that stimulus, as in vomiting up an emetic
drug; at other times, the action of an organ is a general effort to relieve
pain, as in convulsions of the locomotive muscles; other actions drink up
and carry on the fluids, as in absorption and secretion; all which may be
termed efforts of nature to relieve, or to preserve herself.
11. The cure of vertigo will frequently depend on our previously
investigating the cause of it, which from what has been delivered above may
originate from the disorder of any part of the great tribes of irritative
motions, and of the associate motions catenated with them.
Many people, when they arrive at fifty or sixty years of age, are affected
with slight vertigo; which is generally but wrongly ascribed to
indigestion, but in reality arises from a beginning defect of their sight;
as about this time they also find it necessary to begin to use spectacles,
when they read small prints, especially in winter, or by candle light, but
are yet able to read without them during the summer days, when the light is
stronger. These people do not see objects so distinctly as formerly, and by
exerting their eyes more than usual, they perceive the apparent motions of
objects, and confound them with the real motions of them; and therefore
cannot accurately balance themselves so as easily to preserve their
perpendicularity by them.
That is, the apparent motions of objects, which are at rest, as we move by
them, should only excite irritative ideas: but as these are now become less
distinct, owing to the beginning imperfection of our sight, we are induced
_voluntarily_ to attend to them; and then these apparent motions become
succeeded by sensation; and thus the other parts of the trains of
irritative ideas, or irritative muscular motions, become disordered, as
explained above. In these cases of slight vertigo I have always promised my
patients, that they would get free from it in two or three months, as they
should acquire the habit of balancing their bodies by less distinct
objects, and have seldom been mistaken in my prognostic.
There is an auditory vertigo, which is called a noise in the head,
explained in No. 7. of this section, which also is very liable to affect
people in the advance of life, and is owing to their hearing less perfectly
than before. This is sometimes called a ringing, and sometimes a singing,
or buzzing, in the ears, and is occasioned by our first experiencing a
disagreeable sensation from our not being able distinctly to hear the
sounds, we used formerly to hear distinctly. And this disagreeable
sensation excites desire and consequent volition; and when we voluntarily
attend to small indistinct sounds, even the whispering of the air in a
room, and the pulsations of the arteries of the ear are succeeded by
sensation; which minute sounds ought only to have produced irritative
sensual motions, or unperceived ideas. See Section XVII. 3. 6. These
patients after a while lose this auditory vertigo, by acquiring a new habit
of not attending voluntarily to these indistinct sounds, but contenting
themselves with the less accuracy of their sense of hearing.
Another kind of vertigo begins with the disordered action of some
irritative muscular motions, as those of the stomach from intoxication, or
from emetics; or those of the ureter, from the stimulus of a stone lodged
in it; and it is probable, that the disordered motions of some of the great
congeries of glands, as of those which form the liver, or of the intestinal
canal, may occasion vertigo in consequence of their motions being
associated or catenated with the great circles of irritative motions; and
from hence it appears, that the means of cure must be adapted to the cause.
To prevent sea-sickness it is probable, that the habit of swinging for a
week or two before going on shipboard might be of service. For the vertigo
from failure of sight, spectacles may be used. For the auditory vertigo,
æther may be dropt into the ear to stimulate the part, or to dissolve
ear-wax, if such be a part of the cause. For the vertigo arising from
indigestion, the peruvian bark and a blister are recommended. And for that
owing to a stone in the ureter, venesection, cathartics, opiates, sal soda
aerated.
12. Definition of vertigo. 1. Some of the irritative sensual, or muscular
motions, which were usually not succeeded by sensation, are in this disease
succeeded by sensation; and the trains or circles of motions, which were
usually catenated with them, are interrupted, or inverted, or proceed in
confusion. 2. The sensitive and voluntary motions continue undisturbed. 3.
The associate trains or circles of motions continue; but their catenations
with some of the irritative motions are disordered, or inverted, or
dissevered.
* * * * *
SECT. XXI.
OF DRUNKENNESS.
1. _Sleep from satiety of hunger. From rocking children. From uniform
sounds._ 2. _Intoxication from common food after fatigue and
inanition._ 3. _From wine or of opium. Chilness after meals. Vertigo.
Why pleasure is produced by intoxication, and by swinging and rocking
children. And why pain is relieved by it._ 4. _Why drunkards stagger
and stammer, and are liable to weep._ 5. _And become delirious, sleepy,
and stupid._ 6. _Or make pale urine and vomit._ 7. _Objects are seen
double._ 8. _Attention of the mind diminishes drunkenness._ 9.
_Disordered irritative motions of all the senses._ 10. _Diseases from
drunkenness._ 11. _Definition of drunkenness._
1. In the state of nature when the sense of hunger is appeased by the
stimulus of agreeable food, the business of the day is over, and the human
savage is at peace with the world, he then exerts little attention to
external objects, pleasing reveries of imagination succeed, and at length
sleep is the result: till the nourishment which he has procured, is carried
over every part of the system to repair the injuries of action, and he
awakens with fresh vigour, and feels a renewal of his sense of hunger.
The juices of some bitter vegetables, as of the poppy and the laurocerasus,
and the ardent spirit produced in the fermentation of the sugar found in
vegetable juices, are so agreeable to the nerves of the stomach, that,
taken in a small quantity, they instantly pacify the sense of hunger; and
the inattention to external stimuli with the reveries of imagination, and
sleep, succeeds, in the same manner as when the stomach is filled with
other less intoxicating food.
This inattention to the irritative motions occasioned by external stimuli
is a very important circumstance in the approach of sleep, and is produced
in young children by rocking their cradles: during which all visible
objects become indistinct to them. An uniform soft repeated sound, as the
murmurs of a gentle current, or of bees, are said to produce the same
effect, by presenting indistinct ideas of inconsequential sounds, and by
thus stealing our attention from other objects, whilst by their continued
reiterations they become familiar themselves, and we cease gradually to
attend to any thing, and sleep ensues.
2. After great fatigue or inanition, when the stomach is suddenly filled
with flesh and vegetable food, the inattention to external stimuli, and the
reveries of imagination, become so conspicuous as to amount to a degree of
intoxication. The same is at any time produced by superadding a little wine
or opium to our common meals; or by taking these separately in considerable
quantity; and this more efficaciously after fatigue or inanition; because a
less quantity of any stimulating material will excite an organ into
energetic action, after it has lately been torpid from defect of stimulus;
as objects appear more luminous, after we have been in the dark; and
because the suspension of volition, which is the immediate cause of sleep,
is sooner induced, after a continued voluntary exertion has in part
exhausted the sensorial power of volition; in the same manner as we cannot
contract a single muscle long together without intervals of inaction.
3. In the beginning of intoxication we are inclined to sleep, as mentioned
above, but by the excitement of external circumstances, as of noise, light,
business, or by the exertion of volition, we prevent the approaches of it,
and continue to take into our stomach greater quantities of the inebriating
materials. By these means the irritative movements of the stomach are
excited into greater action than is natural; and in consequence all the
irritative tribes and trains of motion, which are catenated with them,
become susceptible of stronger action from their accustomed stimuli;
because these motions are excited both by their usual irritation, and by
their association with the increased actions of the stomach and lacteals.
Hence the skin glows, and the heat of the body is increased, by the more
energetic action of the whole glandular system; and pleasure is introduced
in consequence of these increased motions from internal stimulus. According
to Law 5. Sect. IV. on Animal Causation.
From this great increase of irritative motions from internal stimulus, and
the increased sensation introduced into the system in consequence; and
secondly, from the increased sensitive motions in consequence of this
additional quantity of sensation, so much sensorial power is expended, that
the voluntary power becomes feebly exerted, and the irritation from the
stimulus of external objects is less forcible; the external parts of the
eye are not therefore voluntarily adapted to the distances of objects,
whence the apparent motions of those objects either are seen double, or
become too indistinct for the purpose of balancing the body, and vertigo is
induced.
Hence we become acquainted with that very curious circumstance, why the
drunken vertigo is attended with an increase of pleasure; for the
irritative ideas and motions occasioned by internal stimulus, that were not
attended to in our sober hours, are now just so much increased as to be
succeeded by pleasurable sensation, in the same manner as the more violent
motions of our organs are succeeded by painful sensation. And hence a
greater quantity of pleasurable sensation is introduced into the
constitution; which is attended in some people with an increase of
benevolence and good humour.
If the apparent motions of objects is much increased, as when we revolve on
one foot, or are swung on a rope, the ideas of these apparent motions are
also attended to, and are succeeded with pleasureable sensation, till they
become familiar to us by frequent use. Hence children are at first
delighted with these kinds of exercise, and with riding, and failing, and
hence rocking young children inclines them to sleep. For though in the
vertigo from intoxication the irritative ideas of the apparent motions of
objects are indistinct from their decrease of energy: yet in the vertigo
occasioned by rocking or swinging the irritative ideas of the apparent
motions of objects are increased in energy, and hence they induce pleasure
into the system, but are equally indistinct, and in consequence equally
unfit to balance ourselves by. This addition of pleasure precludes desire
or aversion, and in consequence the voluntary power is feebly exerted, and
on this account rocking young children inclines them to sleep.
In what manner opium and wine act in relieving pain is another article,
that well deserves our attention. There are many pains that originate from
defect as well as from excess of stimulus; of these are those of the six
appetites of hunger, thirst, lust, the want of heat, of distention, and of
fresh air. Thus if our cutaneous capillaries cease to act from the
diminished stimulus of heat, when we are exposed to cold weather, or our
stomach is uneasy for want of food; these are both pains from defect of
stimulus, and in consequence opium, which stimulates all the moving system
into increased action, must relieve them. But this is not the case in those
pains, which arise from excess of stimulus, as in violent inflammations: in
these the exhibition of opium is frequently injurious by increasing the
action of the system already too great, as in inflammation of the bowels
mortification is often produced by the stimulus of opium. Where, however,
no such bad consequences follow; the stimulus of opium, by increasing all
the motions of the system, expends so much of the sensorial power, that the
actions of the whole system soon become feebler, and in consequence those
which produced the pain and inflammation.
4. When intoxication proceeds a little further, the quantity of pleasurable
sensation is so far increased, that all desire ceases, for there is no pain
in the system to excite it. Hence the voluntary exertions are diminished,
staggering and stammering succeed; and the trains of ideas become more and
more inconsistent from this defect of voluntary exertion, as explained in
the sections on sleep and reverie, whilst those passions which are unmixed
with volition are more vividly felt, and shewn with less reserve; hence
pining love, or superstitious fear, and the maudling tear dropped on the
remembrance of the most trifling distress.
5. At length all these circumstances are increased; the quantity of
pleasure introduced into the system by the increased irritative muscular
motions of the whole sanguiferous, and glandular, and absorbent systems,
becomes so great, that the organs of sense are more forcibly excited into
action by this internal pleasurable sensation, than by the irritation from
the stimulus of external objects. Hence the drunkard ceases to attend to
external stimuli, and as volition is now also suspended, the trains of his
ideas become totally inconsistent as in dreams, or delirium: and at length
a stupor succeeds from the great exhaustion of sensorial power, which
probably does not even admit of dreams, and in which, as in apoplexy, no
motions continue but those from internal stimuli, from sensation, and from
association.
6. In other people a paroxysm of drunkenness has another termination; the
inebriate, as soon as he begins to be vertiginous, makes pale urine in
great quantities and very frequently, and at length becomes sick, vomits
repeatedly, or purges, or has profuse sweats, and a temporary fever ensues
with a quick strong pulse. This in some hours is succeeded by sleep; but
the unfortunate bacchanalian does not perfectly recover himself till about
the same time of the succeeding day, when his course of inebriation began.
As shewn in Sect. XVII. 1. 7. on Catenation. The temporary fever with
strong pulse is owing to the same cause as the glow on the skin mentioned
in the third paragraph of this Section: the flow of urine and sickness
arises from the whole system of irritative motions being thrown into
confusion by their associations with each other; as in sea-sickness,
mentioned in Sect. XX. 4. on Vertigo; and which is more fully explained in