In evolving the idea of time, as in that of space, we must first examine
the concrete fact which is its starting-point, i. e., real _duration_;
next the concept which is extracted from it, time _in abstracto_—and this
must be followed in the successive stages of its development.
I.
Real, concrete duration is a quality known by itself, included among
internal and external sensations, as later on in the representations
which psychology, in what concerns it, must accept as an ultimate datum.
What is this concrete duration, furnished by experience? It might
strictly be said to be the present; yet this answer is somewhat
theoretical, for it must be admitted that what we term “the present” has
vague and fluctuating limits. Moreover, its clear and precise distinction
from what has preceded and what is to follow it—the past and the
future—is a somewhat late production. Of this we have objective witness
(see Ch. II.) in primitive languages, during the period in which the
value of the verbs was undetermined. Take again the fact, as frequently
observed, that children even at the age of three, or older, having
vague notions of past and future, make a general confusion, and do not
distinguish between “yesterday” and last week, between “to-morrow” and
next week (Sully).
Still, we must admit that the present has the privilege of appearing
in consciousness as the typical duration, the standard, the measure to
which everything must be referred. Nor can this be otherwise, seeing
that (as is too often forgotten) we live only in the present; that the
past and the future have no existence for us, are only known to us under
the condition of becoming present, of occupying _actual_ consciousness.
The present is the only psychical element, which, consciously or
unconsciously, gives a content and reality to duration.
It is essential to rid ourselves of the opinion accredited by many
authors, that the present is only an elusive moment, a transition,
a passage, a flash, a mathematical point, a zero, a nullity; on the
contrary—it alone has duration, is now long, now short. It is even
possible, to some extent, to determine its limits, and to transcend
this vague description. Here we are aided by the labors of the
psycho-physicists. We may say that this study, long restricted to
metaphysical dissertations, entered upon a positive phase with Czermak,
who (in 1857) opened out a new line, in which he has been followed by
many others. The numerous researches and experiments made upon the
“sense of time” may be omitted without prejudice to our subject, while
the discussion of them would deter us from our principal aims. We
must, however, give a rapid summary of those which relate either to the
actual perception of duration, or to the reproduction in memory of past
duration.[105]
1. This present, declared to be inapprehensible, has however been
determined as regards its _minimum_ duration. For the discrimination
period between two different sensations (taken as the type of the
briefest and simplest psychical act), Kries and Auerbach found durations
varying between 0·01 and 0·07 second with an average of 0·03 second. At
a later period, Exner, experimenting with Savart’s wheel, stated that
the interval at which two successive taps can be perceived separately
may be reduced to 0·05 second: as also for the sound produced by two
electric sparks. For the eye, the minimum perceptible interval between
two impressions falling on the yellow spot, is 0·044 second. Below this,
one of the conditions necessary to consciousness—an adequate duration—is
wanting.
Certain experiments contributed by Wundt and his pupils throw light also
upon the _maximum_ duration that can be apprehended by consciousness.
They made use, almost exclusively, of auditory sensations, which are more
closely allied than any others to the sense of time. Wundt finds that
twelve impressions equivalent to a duration varying from 3·6 to 6 seconds
can be clearly perceived to form a group. Dietze admits the continuous
perception of 40 beats of the metronome, provided the mind arranges them
spontaneously in 5 sub groups of 8, or 8 sub-groups of 5. Total duration:
12 seconds. Others vary in their conclusions from 6 to 12 seconds and
even more.[106] James is inclined to think that the actual present may
extend to a _minute_.
Of course these figures, of which we can only give a few, vary with the
subjects, quality of the impressions received, conditions of experience,
exercise, etc. Nor must we forget that these laboratory researches are
somewhat artificial, and concerned with the perception of “the present”
under studied conditions of simplicity which are not precisely those of
spontaneous consciousness. Still it is plain that “the present” is by
no means an abstraction, a nothing, and we may conclude, in the words
of James, “by saying that we are constantly conscious of a certain
duration—the specious, present—varying in length from a few seconds
to probably not more than a minute, and that this duration (with its
content perceived as having one part earlier and the other part later)
is the original intuition of time. Longer times are conceived by adding,
shorter ones by dividing, portions of this vaguely broached unit, and are
habitually thought by us symbolically.”[107]
2. Experiments relating, not to consciousness of actual duration, but
to the _reproduction_ of durations, and determination of the errors
involved, are numerous, and contradictory. I refer to them in passing
only because they are eminently suited to show the very relative and
precarious character of our concrete notions of duration.
Through all divergencies, the formula enunciated by Vierordt, the
principal initiator of these researches, remains stable; our
consciousness of time comes, not from a sensation, but from a judgment,
and in our retrospective appreciation of duration, we diminish intervals
that are long, and increase those that are short. The debates and
disagreements of the experimenters relate above all to the determination
of the “indifferent point.” Vierordt denoted by this term the interval
of time which we appreciate the most exactly, which we have no tendency
to lengthen or abridge, so that if we are required to repeat it
experimentally, the error is nil, or very rare. This duration, reproduced
according to reality, is 0·35 sec. (according to Vierordt and Mach); 0·4
sec. (Buccola); 0·72 sec. (Wundt); 0·75 sec. (Kollert); 0·71 sec.; etc.
According to another author, Glass, there is a series of points at which
we find maximum relative accuracy; 1·5 sec., 2·5 sec., 3·75 sec., 5 sec.,
6·25 sec., etc. Münsterberg again criticises the entire series of figures
and experiments, for reasons that will be given below.
Independent of these experiments, which are restricted to very simple
events, the facts of our daily life show to superabundance that our
memory of duration is almost always inexact. Thus it has often been
remarked that the years seem to be shorter with advancing age: which is
again an instance of abbreviation of the longer intervals.[108] It is
hardly necessary to say that our appreciation of duration (concrete),
like that of extension (concrete), depends upon multiple conditions, and
varies with these. Such are pre-eminently constitution and temperament:
compare a phlegmatic with a nervous individual; an Oriental for whom
time is not, with an Occidental, agitated by a feverish existence. Add
to these, age, number, and vivacity of impressions received, certain
pathological states, etc., and we find here, as for space, that the
variability of concrete knowledge is opposed to the fixity of the concept.
This consciousness of duration, fluctuating, variable, and unstable as
it may be, is nevertheless the source whence our abstract notion of time
is derived: but whence comes it, itself? Where does it originate? “Time
has been called an act of mind, of reason, of perception, of intuition,
of sense, of memory, of will, of all possible compounds and compositions
to be made up from all of them. It has been deemed a General Sense
accompanying all mental content in a manner similar to that conceived of
pain and pleasure.”[109]
Here are many answers. We may add that among these supposed origins some
authors admit only one, to the exclusion of the rest, though nothing
justifies them in such arbitrary selection.
Some prefer _external_ sensations, inasmuch as they give us the
consciousness of a sequence. Hearing has been termed the sense of time
_par excellence_. This thesis has notably been sustained by Mach:[110]
since in a melody we can separate the rhythm from the sounds which
compose it, he concludes that rhythm forms a distinct sequence, and that
there must be in the ear, as in the eye, a mechanism of accommodation
which is perhaps the organ of the “time-sense.” Others decide in favor
of the general sense, touch, capable in all animals of receiving a
succession of impressions at once distinct and forming a series. Sight,
with its fine and rapid perception of movements and changes, is an
organ admirably adapted to the formation of relations of sequence, the
constitutive elements of time. Were not, moreover, the first essays at
determining time (succession of days and nights, seasons, etc.) founded
upon visual perceptions?
The majority of contemporary psychologists are, however, inclined
with reason to seek the principal origin of the notion of duration
in _internal_ sensations; and these derive their prerogative from
the primordial and rhythmical nature which pertains to the principal
functions of life.
“A stationary creature,” says Herbert Spencer, “without eyes, receiving
distinct sensations from external objects only by contacts which happen
at long and irregular intervals, cannot have in its consciousness any
compound relations of sequence save those arising from the slow rhythm
of its functions. Even in ourselves, the respiratory intervals, joined
sometimes with the intervals between the heart’s pulses, furnish part of
the materials from which our consciousness of duration is derived; and
had we no continuous perceptions of external changes, and consequently
no ideas of them, these rhythmical organic actions would obviously yield
important data for our consciousness of Time: indeed, in the absence of
locomotive rhythms, our sole data.”[111]
“Rhythm,” to quote Horwicz, “is the measure, and the sole measure, of
time; a being incapable of regular periodic intervals could not attain to
any conception of time. All the rhythmic functions of the body subserve
this end: respiration, pulse, locomotor movements, hunger, sleep, work,
habits and needs of whatever kind.”—Guyau maintains essentially the same
thesis, under a more metaphysical aspect: “Time is embryonically in
primitive consciousness; under the form of force and effort; succession
is an abstraction of motor effort, exerted in space. The past is the
active become passive.”[112]
More recently, Münsterberg[113] has attributed a preponderant and almost
exclusive part to respiration. Although he affirms that the origin of
our notions of duration must be sought in our consciousness of muscular
effort in general, and that its primitive measure lies in the rhythm
of the bodily processes; yet the gradual rise and fall of the sense of
effort which accompanies the two phases of the respiratory function
(inspiration, expiration) seem to him the principal source of our
appreciation of duration. After a rather sharp criticism of the attempts
of his predecessors (which we have already reviewed) to determine the
“indifferent point,” he maintains that their disagreements were caused by
incomplete comprehension of the psychical events produced in the course
of experience. In the perception of the successive beats of a metronome,
or taps of Wundt’s electric hammer, only the auditory impressions are
attended to; this is a mistake. It is supposed that the sensation-limits
form the entire content of consciousness, and that the intervals between
them are empty. On the contrary, they are filled by an act of attention.
We are conscious of a process of variable tension which, from the
initial moment, goes decreasingly towards zero, and then rises again, to
adapt itself to the sonorous impression that should follow it. In other
words, there are, in the perception of three successive taps, not three,
but _five_ states of consciousness: three external and two internal
sensations. We must reckon thus if we are rigorously to determine the
_psychological_ conditions of experience. As evidence, Münsterberg brings
forward the following results, which are from his own experiments.
The “normal time” is first determined, i. e., the standard of duration
that should be reproduced by the experimenter as exactly as possible
(“time of comparison”).
In one case, different durations were given, such as 15, 7, 22, 18 secs.,
etc., without attending to the respiration (expiration or inspiration)
of the subject, who reacted independently of it. In the reproduction of
normal time, the mean error was 10·7 per cent.
In the second case, the same numbers were given again, but care was taken
that the subject began his estimation at precisely that respiratory
period which coincided with the beginning of the normal time. The mean
error did not now exceed 2·9 per cent.
In the two cases cited, there was no interruption between the
determination of the normal time and its reproduction; the two operations
succeeded each other immediately. If, on the contrary, a short pause, or
arrest, was introduced between the two, varying from 1 to 60 seconds, the
results are—proceeding at random as in the first case—a mean error of 24
per cent.; as in the second, a mean error of 5·3 per cent.
Münsterberg has been not unreasonably reproached for attributing to
respiration, among all the other internal sensations, the exclusive
privilege of measuring time. A less justifiable criticism asserts that
his thesis is devoid of value because we can appreciate the variations
in duration in the beats of a clock more readily than the changes in the
rhythm of respiration. This is confounding two distinct factors in the
genesis of the idea of duration: its period of formation and its period
of constitution; that which occurs at the commencement, and that which
takes place in the adult. Our measure is at first subjective, variable;
progress consists in the substitution of a fixed, objective measure.
Doubtless, the latter is superior in clearness and in precision; yet this
is no proof, not even presumption, that it is first in order: we shall
return to this point later on.
In short, our consciousness of duration is a complex state, more exactly,
a process—since it is less a state than a becoming. The rhythmical
visceral sensations are its core; it is an internal chronometer, fixed
in the depths of our organisation. Around this subjective element, other
objective elements are added and co-ordinated—the regular sequences which
are caused by external sensations. They form the sheath of the core, and
constitute the sensible portion of our consciousness of duration, not,
however, its totality.
II.
Until now we have considered time under its concrete form alone, whether
given as an actual event in consciousness, or revived as a past event
in memory. We have now to follow the complete development of this idea
to its extreme limit. In this study we may conveniently distinguish two
stages:
The first, which depends on memory and imagination, consists in thinking
a certain extension of duration, that may be more or less vaguely
represented: a day, a week, a year, etc.
The second, which depends on abstraction alone, gives time in general,
the pure concept, which cannot be represented, and is determined by signs
alone.
FIRST STAGE.—Certain minds never get beyond this first stage. In respect
of time, this corresponds to the lower forms of abstraction which we
have so often designated by the terms, _generic image_ and, at a higher
degree, _concrete-abstract notions_ (intermediate abstracts).
The lowest form, which is just higher than the recognition of concrete
duration, results like the generic image from the repetition of a
sequence of events that recur constantly, and are approximately uniform.
They are series of which the terms are variable, but which begin and end
always in the same manner. Such are the appearance and disappearance of
the sun, lying down to sleep and waking up again, and similar facts of
common life. The points of departure, the start and finish, are always
the same, whatever the variations in the intermediate states. These
generic images are met with among the higher brutes, children, and
primitive races.
To what extent are the higher animals capable of having a certain
representation of time, constructed from their experience of real
duration? This is an obscure problem which has been little studied. We
are not of course referring to time _in abstracto_, to the concept, but
to the recognition of certain often repeated cycles. Many animals are
known to have an approximate appreciation of sufficiently protracted
periods, supplied by the periodicity of their needs (hours at which they
get food, are taken out, etc., etc.). Prejudice apart, we know of others
which, in addition to this subjective physiological knowledge, possess a
fairly exact notion of certain regular and objectively caused periods,
determined by the progress of natural phenomena, especially by the path
of the sun.[114]
In all these instances we may assign as cause, the incontestable
preponderance (in animal life) of automatism and of routine: which is
equivalent to saying that the notion of these durations is formed by a
passive assimilation, and this—as we have seen—is the creative process of
generic images.
According to some authors, there are instances of exact appreciation
of much less simple periods. Brehm says that during a long passage
an ourang-outang visited the sailors every Wednesday and Friday at 8
o’clock, because on those days sago, sugar, and cinnamon were served
out, of which he got his share. An anecdote has often been cited after
Romanes, of “the geese who came regularly every fortnight, from afar, the
morning after the market, in a small English town, to pick up the corn
scattered on the marketplace. One year the market was postponed for a day
of national humiliation, but the geese came as usual.”[115]
These and other analogous facts seem scarcely sufficient in number, nor
strictly enough observed, to warrant any scientific conclusion.
We have previously remarked that, up to the age of three years or more,
children who already have an approximate knowledge of space relations,
(distance, proximity, within, without, upper, lower, etc.) have a very
confused notion of periods as short as three to four days, a week, etc.
It has been hypothetically suggested that the extension of the notion of
duration must for them arise in expectation rather than in memory, in an
orientation towards the future rather than the past.
The concrete-abstract period with its different degrees, limited on the
one extreme by generic images, on the other by the pure concept, is met
with among savage races, and in rising civilisations. It is a stage that
has to be traversed by every human race; many now existing have not
got beyond it. Days (solar revolution), months (lunar revolution), and
seasons, the round of the changing aspects of nature, give the primitive
and simplest notions of time in extension. No tribe is so low in the
scale as not to have reached this level. The determination of the (solar)
year, even when only approximate, marks a decisive progress.
The peculiar feature of this period, in its lowest degrees, is that
the notion of time cannot as yet be separated, or extracted, from the
sequence of events. We have already given many examples of this state of
intelligence. It is not poetical feeling that makes the savage reckon
the age of his children by the flowering of certain plants (and other
analogous locutions abound among primitive races,)—nor any innate taste
for metaphor: it is merely that he requires concrete marks to determine
duration. He cannot think the longer periods _in abstracto_; they must
be imagined, represented in virtue of a more or less arbitrary choice,
imprisoned in a concrete mould. Moreover, in the absence of any extended,
coherent, systematic numeration, the mind loses itself after the first
step. It lacks the necessary vehicle for movement in front and behind,
knowing whither it is tending. The natural phenomena which it takes as
its starting-point are poor substitutes for the absent sign, and moreover
rivet it invincibly to the concrete.
In my opinion, the culminating point of this period is arrived at in the
popular conception of time—considered as a vague entity which unrolls
itself, as it gives birth to events. This is the notion that is general
among most men of medium culture, who are ignorant of philosophical
speculation on the subject. It is the final term of common, spontaneous
reflexion, left to its own resources. Thus it is said of time that it
brings the unexpected, consoles sorrow, extinguishes passion, changes
tastes, solves difficulties, and the like; it seems to be an active
power, a thing in itself. In fact, no other abstraction has perhaps
been so often reified. We may further remark that time has often been
personified and even deified in several religions. Such an honor has
never been conceded to space. The cause of this difference is that time
has an internal, human character: above all, that it is opposed to
space as dynamic to static. It is an entity manifested in movement and
change, and thereby essentially acting and living. While, in the popular
conception, space is the _passive_ receptacle of bodies, time is the
_active_ spring by which the whole is set in motion.
SECOND STAGE.—The generic images of duration, and later, the
semi-concrete, semi-schematic representation of more prolonged lapses
of time, provide the material whence we obtain the purely abstract
concept of time. It was stated above (p. 153) that the true concept of
space was constituted on the day when the ancient geometers disengaged
from the different extensions, the essential features which they termed
dimensions. So must the first astronomers, without knowing or seeking for
what they did, have laboriously disengaged the essential characteristics
of time conceived _in abstracto_. First, they purified the notion of
duration from all anthropomorphic features, studying it objectively, in
the course of the regular phenomena of nature. Moreover, they introduced
measure. The Chaldæans of Alexander’s time, who possessed a series
of astronomical observations embracing a period of 1,900 years, who
made an error of only two minutes in their computation of the sidereal
year, who determined a cycle of 6,585 days by which they were able
to calculate eclipses;[116] who were later on the inventors of the
clepsydra, hour-glass, and other more or less imperfect instruments for
measuring the subdivisions of the day; all these counted for more than
metaphysical speculation in ridding our subject of popular conceptions—or
at least to a large extent prepared the way. Accustomed as we are in
civilised life to a convenient and exact knowledge of the flow of time,
measuring it off at any moment by clocks and watches, we forget how
widely different must be the state of mind in the man whose only guides
are approximations: such, e. g., as the varying height of the sun in
different seasons, with other natural changes apt to be misinforming.
The one life is precise, the other vague, or at least mysterious. That
our measure of time (as of aught else) is relative, matters little, and
the vexed problems of this subject do not concern us. By measure, the
notion of time acquires a _quantitative_ mark; it no longer appears as
an entity, but as a possibility of successive events, as a divisible
and subdivisible process; as an extract or abstract, set apart from the
events, dissociated from them by an intellectual operation: in short—time
is a thing no longer real or imaginary, but _conceptual_.
It is wasted labor to repeat for time what has already been said for
space, and is applicable to both concepts. Time, like space and number,
can be conceived as illimitable; but here again the infinity is only
in our mental operation. We can add century to century, million upon
million of years. This infinite time is potential only—constituted by a
two-fold process: either as a sequence of numbers, which is the ordinary,
simplest, and most abstract proceeding; or by filling it with fictitious
events, with arbitrary constructions, for the future; by evoking the
image of vanished states, when we go back to the first geological ages of
our globe, to the nebulous period, and so on. This conception of infinite
time is however quite subjective, and in itself reveals nothing as to the
nature of things: we do but add one state of consciousness to another; it
is an inexhaustible possibility of progression and retrogression; and it
is nothing more.
It is a common illusion to transform this conceived infinity into a real
infinity; we forget that the mind is only working upon the abstract, i.
e., upon a fiction, useful no doubt, but created by ourselves alone,
according to our intellectual nature.
Let us suppose that, in consequence of gradual cooling, the disappearance
of the sea, or any other cause, man and all animals capable of
appreciating duration were to disappear from the surface of the earth;
time would disappear with them. Doubtless the earth would continue to
turn round its axis, the moon round our planet, the sun to take its
course; yet nothing would exist beyond the movements. Just as—if every
eye were to disappear—there would be neither light nor color; if every
ear failed, there would be neither sounds nor noises, but only the bare
potentiality of luminous and auditory sensations if the appropriate
organs were to appear again: so, on our hypothesis, there could only be a
potentiality of time.
Consciousness is the necessary condition of any notion whatever of the
time which appears and disappears with it.
* * * * *
It is no part of our subject to discuss the various theories that have
been advanced as to the nature of the psychological process by which the
primitive notion of time is constituted in consciousness. This question
is, on the one hand, distinct from the history of its development as an
abstract idea, which we have been endeavoring to follow, and, on the
other, from all hypotheses as to its ultimate origin (Kant’s _à priori_
form, Renouvier’s law of the mind, Spencer’s cerebral innateness) which
explains neither its appearance as a fact, nor its genesis in experience.
We may, however, complete our account by summarising the latest
psychological opinions.[117]
It is clear that a simple sequence of impressions will not suffice to
constitute the idea of time; the series must be cognised as such, felt
or thought as a sequence. How is it to be cognised? Contemporary opinion
upon this point appears to be capable of reduction into two principal
types.
1. Some admit, as adequate conditions, sensations and their consecutive
images, strong states and weak states; provided, however, that the latter
arise before the former have disappeared from consciousness.
Wundt supposes that similar beats of a clock succeed each other at
regular intervals in a vacant consciousness. When the first has
disappeared its image remains until the second succeeds it. This
reproduces the first, in virtue of the law of association by similarity,
but at the same time encounters the still persisting image. Hence
the simple repetition of the sound contains all the elements of
time-perception. The first sound (recalled by association), gives the
commencement, the second the end, and the persistent image represents
the length of the interval. At the moment of the second impression, the
entire perception of time exists simultaneously, since all the elements
are presented together: the second sound and the image directly, and the
first impression by reproduction.
“The phenomena of ‘summation of stimuli’ in the nervous system prove,”
says James, “that each stimulus leaves some latent activity behind
it which only gradually passes away. Psychological proof of the same
fact is afforded by those ‘after-images’ which we perceive when the
sensorial stimulus is gone.... With the feeling of the present thing
there must at all times mingle the fading echo of all those other
things which the previous few seconds have supplied. Or, to state it in
neural terms, _there is at every moment a cumulation of brain-processes
overlapping each other, of which the fainter ones are the dying phases
of processes which but shortly previous were active in a maximal degree.
The amount of the overlapping determines the feeling of the duration
occupied_.... Why such an intuition should result from such a combination
of brain-processes, I do not pretend to say. All I aim at is to state
the most _elemental_ form of the psycho-physical conjunction.” James
is careful to repeat in several places that he makes no attempt at
_explanation_.
2. Others admit sensations and intervals; sensations that are no longer
images, but internal sensations of tension, of effort; more properly
a subconscious element, which consciousness is able to apprehend by
observation or induction. This theory has a more active character than
that first discussed.
The cleanest and most complete form of this interpretation is that of
Münsterberg,—as set forth above.
Fouillée supports the same thesis as a particular case of his general
theory of _idées-forces_. The apparent present is a synthesis of real
presents. Our primitive perception is of change, not of stability; we are
conscious of transition. The static point of view must be completed by
the dynamic.
The complete separation of present and past is a mathematical fiction.
The sum of transition which is a factor in appetite aids in forming the
series. Time is a form of appetite; beneath the floating image there is a
tendency to movement. A non-volitional being would have no representation
of time: time is a form of appetition.[118]
“It is probable,” says Mach, “that time sensation is connected with the
organic _consumption_ necessarily associated with consciousness,—that
we feel the _work of attention_ as time.... The fatiguing of the organ
of consciousness goes on continually in waking hours, and the labor of
attention increases just as continually. These sensations connected with
greater expenditure of attention appear to us to happen later.”[119]
Others again (Waitz, Guyau, and more particularly Ward) admit _temporal
signs_ in imitation of Lotze’s “local signs.” Our successive acts of
attention leave a series of residua, variable in intensity and precision;
these “temporal signs” permit the conception of representations as
successive, and no longer as simultaneous. “What is this distance that
separates _A_ from _B_, _B_ from _C_, and so on?... It is probably that
the residuum of which I have called a temporal sign; or, in other words,
it is the movement of attention from _A_ to _B_.”[120]
These extracts will suffice to show the character of the second theory,
which seems to me the more acceptable. It is the more complete, inasmuch
as it takes into consideration, not only the clear states, existing in
consciousness, but the subconscious states also; it is not confined to
intellectual elements alone (sensations and images), but recognises the
necessary rôle of the active, motor elements.
Moreover, it seems more apt than the other to explain certain facts
of current experience. It is a matter of common observation that time
seems long to us, under two contrary conditions: (1) when it is very
long; (2) when it is very empty. Here we have an apparent psychological
contradiction. The two cases, however, are equally explained by the
quantity of the states of consciousness: the first is filled with
events, the second, with efforts. After three or four days of a journey
fertile in incident, one seems to have left home a long time, because
(in comparison with three or four days of ordinary life) the quantity
of adventures held in mind, each implying a _quantum_ of duration,
appears to us in sum as an enormous duration. On the other hand, to the
prisoner incarcerated in a cell, to the traveller at a deserted station
waiting for a train; briefly, to all who are in the state known by the
name of expectant attention, time seems to be of immeasurable extension.
This is because there is a constant expenditure of effort, a tension
incessantly renewed, incessantly frustrated; consciousness is nearly void
of representations, while it is filled with acts of attention constantly
repeated. This instance of time prolonged, while apparently empty, is
difficult to explain, if only the intellectual elements are taken into
consideration, omitting the consciousness of motor states. It should be
noticed that “full” time seems longer in the past; “empty” time, in the
present and immediate past; perhaps because the former rests principally
upon intellectual memory, which is stable; the latter, upon motor memory,
which is vague and fragile.