THE BLOOD THE SEAT OF THE SOUL
No doctrine of Harvey sounds stranger to a biologist of to-day than
his doctrine that the blood is the seat of the soul; nor does any
other belief of the great discoverer reveal him more clearly to be a
link between the old and the new; not simply an innovator who fixed
a gulf between them. We have heard him explicitly deny in his old
age the Aristotelian doctrine that the heart "is endowed with soul."
We have seen that thirty-five years earlier he had jotted down in
his note-book these words: "The soul is in the blood."[271] Let us
study him now as he lays stress, not merely on the primacy of the
blood, but on its psychological endowments.
Thirteen years before the date of Harvey's note-book Shakspere's
play of "Hamlet" had appeared in print; in which the prince speaks
thus of following his father's ghost:--
"Why, what should be the fear?
I do not set my life at a pin's fee;
And, for my soul, what can it do to that,
Being a thing immortal as itself?"[272]
It has been foreshadowed that for Harvey, the graduate of
Cambridge and of Padua, the physician of the Renaissance, the word
"_anima_"--"soul"--did not simply mean the immortal part of man,
as for Hamlet, but was equivalent to the "_psyche_" of ancient
philosophy. In order, therefore, readily to follow Harvey's thought
at this juncture, we must first, like him, go to the fountain head;
for only sayings of Aristotle can give us a sufficient clue to what
he, and after him Harvey, meant by "soul."
Aristotle says in his treatise On Soul:--
"Some natural bodies have life and some have not. By life we
mean the being nourished, and growing, and decaying, of oneself."
In the same treatise he says further:--
"The soul is that by which primarily we are alive, and
display sensation and intellect; ... but it is not matter and
substratum."
Again he says:--
"Were the eye an animal, vision would be the soul thereof; for
reason indicates that vision is the essence of the eye.[273] The
eye in its turn is the material [basis] of vision; which latter
failing, the eye is not an eye except in name, like an eye of
stone or in a drawing."
The doctrines of the foregoing three passages are developed and made
more explicit in the following, still from the treatise On Soul:--
"It is the presence of life, we say, which makes the difference
between that which has soul and that which has not. To amplify
regarding life: we call anything alive which possesses even a
single one of the following: intellect, sensation, motion and
rest in space, and also the motion[274] involved in nutrition,
and both decay and growth. Therefore, even all the plants are
held to be alive."
A few lines further on Aristotle says, speaking of the power or
faculty[275] of taking nourishment:--
"This can exist without the others, but not the other faculties
without this, in mortal beings. The aforesaid is clear in the
case of plants; for they possess no other faculty of the soul.
To this faculty then life owes its origin in living things; but
the being an animal owes its origin primarily to sensation;
for beings that neither move nor change their place but yet
possess sensation, we call animals and not merely living things.
The primary sense, which exists in all, is touch; and just as
the nutritive faculty can exist without touch or sensation of
any kind, so can touch exist without the other senses. The
"nutritive" is our term for such part of the soul as is shared
even by plants, all animals, however, evidently possessing the
sense of touch. The cause of the presence of each of the two
aforesaid shall be told later. Now let us only go so far as to
say that the soul is the source of the [faculties] aforesaid,
and is defined by means of them, to wit: the nutritive, the
sensory, the intellectual, the motor.[276] As to whether each of
these is a soul or is a part of the soul; and if a part, whether
in the sense that it is only separable by reasoning,[277] or
locally as well--as to some of these points, it is not hard to
see our way, but some present difficulties."[278]
If we turn to Aristotle's treatise On Generation we find him dealing
with the relations of the body to the nutritive soul, in virtue
whereof the body is alive; with its relations to the sensory soul,
in virtue whereof it is an animal body; and, finally, in man with
its relations to the intellectual soul. Of these three kinds of
soul or parts of the soul, he concludes, the mind "is alone divine;
for in the working thereof no bodily working is involved."[279]
Only soul of this divine quality does he admit to be separable from
body.[280]
The master has spoken. Now let the great pupil speak. In the last
Exercise but one of his treatise On Generation, Harvey says,
referring to the blood:--
"It assuredly contains the soul first and foremost, not only
the nutritive, but the sensory soul as well, and the motor. The
blood penetrates in all directions and is present everywhere;
if it be taken away, the soul itself is made away with
also and at once; so that the blood would seem to be wholly
indistinguishable from the soul or, at least, should be reckoned
the substance of which the soul is the activity. The soul I aver
to be such that neither is it body at all, nor yet entirely
without body, but comes in part from without, in part is born
on the premises,[281] and in a manner is part of the body;
in a manner, however, is the origin and cause of everything
within the body of an animal, certainly of nutrition, sense,
and motion, and hence, in like manner, of life and death; for
whatsoever is nourished, that same is living, and _vice versa_.
So, likewise, whatsoever is nourished abundantly, increases; but
whatsoever too sparingly, dwindles; and whatsoever is nourished
perfectly, keeps its health; whatsoever otherwise, lapses into
disease. Therefore, as is the soul, so also is the blood to be
reckoned the cause and author of youth and old age, of sleep
and of waking, and even of respiration also--especially in view
of this, that in the things of nature the first instrument
contains within itself an internal moving cause. Therefore, it
comes to the same whether one say that the soul and the blood,
or the blood together with the soul, or, if preferred, the soul
together with the blood, bring everything within an animal to
pass."[282]
Only two years before these words were published the aged Harvey had
said the following:--
"Nor does the blood possess vigor, faculty, reason, motion, or
heat, as the gift of the heart."[283]
A comparison of the foregoing passages from Harvey with the
preceding passages from Aristotle makes it clear that, for Harvey,
although the soul dwells no longer in its Aristotelian seat, it is
no other than the Aristotelian soul which pervades the "principal
part" of the body, the living blood of the Harveian circulation.
What proofs does Harvey offer that the soul is in the blood? He has
offered already one weighty piece of evidence noted by many from
of old in the chase, in butchery, in sacrifice, in battle--the
evidence from fatal hæmorrhage. This had been set forth nineteen
centuries before him by one of his Hippocratic predecessors, who had
referred to the reasoning
"used by those who say that the blood is the man; for, seeing
men slaughtered and the blood running out of the body, they
conclude that the blood is the soul of man."[284]
Presently Harvey himself shall tell us that in placing the soul in
the blood he is consciously reaffirming one of the most ancient of
beliefs; but he is far from basing his adhesion to it merely on such
immemorial evidence, known to all, as the result of loss of blood,
for he also adduces once more his own observations of the early
embryo of the fowl, to prove not only the primacy of the blood but
the presence of the soul therein. His testimony follows, and in
reading it one must bear carefully in mind that in Harvey's time
no clear scientific distinction had yet been worked out between
movements which imply sensation, and movements, whether reflex or
not, which do not depend upon consciousness. In his treatise On
Generation Harvey says:--
"For my own part I am sure from numerous experiments that not
only motion is inherent in the leaping point,--which no one
denies--but sensation also. For you will see this point thrown
into varied commotion and, as it were, irritated, at any touch
whatever, even the slightest, just as sensitive bodies in
general usually give evidence of sensation by movements proper
to themselves. Moreover, if the injury be repeated often, the
leaping point becomes excited and the rhythm and order of its
pulsations disturbed. In like manner do we infer the presence
of sensation in the so-called sensitive plant and in zoöphytes,
from the fact that when they are touched they draw themselves
together as though taking it ill.... So there is no doubt that
the leaping point lives, moves, and feels like an animal."[285]
In a later part of the same treatise he says:--
"It is manifest that all motion and sensation do not proceed
from the brain, since we plainly perceive the presence of motion
and sensation before the brain has come into existence; what
I have related proves that clearly sensation and motion dawn
forthwith in the first droplet of blood in the egg, before a
vestige of the body has been formed. Moreover, in that first
state of the structure or constitution of the body which I have
called the mucilaginous, before any members are discernible and
when the brain is nothing but limpid water, if the body be only
lightly pricked it moves, contracts, and twists itself obscurely
like a worm or caterpillar; so that it gives clear evidence of
sensation."[286]
In another Exercise of the same treatise he says:--
"It is evident also from the generation of the chick, that
whatever the source of its life or the vegetative first cause of
it may be, this had a prior existence in the heart. Wherefore,
if the said first cause be itself the soul of the chick, it
stands proved likewise that this had a prior existence in the
leaping point and the blood; seeing that we observe therein
motion and sensation; for it moves and leaps like an animal. If,
then, there exist in the leaping point the soul, which (as I
have taught in my account) constructs for itself the rest of the
body, nourishes and increases it, certainly from the heart as
from a fount the soul flows out[287] into the entire body.
"So, likewise, if the egg be prolific because there is a soul
in it, or (as Aristotle would have it) the vegetative part of
the soul, it is clearly proved that the leaping point, in other
words the generative part endowed with soul, springs from the
soul of the egg, for nothing is the author of itself, and that
the soul is transferred from the egg to the leaping point, next
to the heart, and then to the chick."[288]
In still another chapter of his treatise On Generation Harvey
says:--
"Nor does the blood deserve to be called the original[289] part
and the principal part, merely because in it and by it motion
and pulsation are originated, but also because in the blood the
psychical heat first comes into existence, the vital spirits
are generated, and the soul itself inheres. For wherever the
immediate and principal instrument of the vegetative faculty is
first found, there probably the soul also is first present and
takes its origin thence; since the soul is inseparable from the
spirits and the innate heat....[290]
"The life then inheres in the blood (as we read also in Holy
Writ),[291] because therein the life and the soul are manifest
first and fail last....[292]
"It stands clearly proved that the blood is a generative part,
the source of life, the first to live and the last to die, the
primary seat of the soul; that in the blood, as in its source,
the heat first and chiefly abounds and flourishes; and that by
and from the blood all the other parts of the whole body are
fostered and obtain their life by means of the influx of heat.
Indeed, the heat which accompanies the blood floods, fosters,
and preserves the entire body, as I have demonstrated already in
my book on the motion of the blood."[293]
Harvey's proof that the blood is "the first to live and the last to
die," we have scanned already in an earlier chapter of this paper.
In the next chapter of his treatise On Generation he says:--
"No heat is to be found, either innate or inflowing, other than
the blood, to be the soul's immediate instrument."[294]
On the next page, after briefly making certain suppositions, he says
further:--
"Why should we not affirm with equal reason that there is soul
in the blood; and also, since the blood is the first thing
generated, nourished, and moved, that out of the blood the soul
is first evoked and kindled? Certainly it is the blood in which
vegetative and sensitive workings first come to light; in which
heat, the primary and immediate instrument of the soul, is
innate; it is the blood which is the common bond of body and
soul, and in which as a vehicle soul flows into all parts of the
whole body."[295]
But no matter how far on high the blood may have been exalted by
Harvey the physician and psychologist, it is still subject to the
lancet of Harvey the clinician, the heir of Hippocrates; for in his
treatise On Generation, in the same Exercise with the foregoing
passage, occurs the following:--
"While I assert that the seat of the soul is in the blood,
first and foremost, I would not have the false conclusion drawn
from this that all blood-letting is dangerous or hurtful; nor
have it believed, as the multitude believes, that just to the
degree that the blood is taken away does the life pass away at
the same time, because holy scripture has placed the life in
the blood. For it is known from everyday experience that the
taking of blood is a wholesome aid against very many diseases
and is chief among the universal remedies; seeing that depravity
of the blood, or excess thereof, is at the bottom of a very
great host of diseases; and that the timely evacuation of
blood often brings exemption from most dangerous diseases and
even from death itself. For just to the degree that the blood
is taken away as our art prescribes, is an addition made to
life and health. This very thing has been taught us by Nature,
whom physicians set themselves to imitate; for Nature often
makes away with the gravest affections by means of a large
and critical evacuation by the nares, by menstruation, or by
hæmorrhoids."[296]
Not only does Harvey affirm that "the soul is in the blood" and, as
we have seen, appeal to observation and experiment in support of
this doctrine; but he refers to those who had believed it before
him, and maintains it against Aristotle's express denial. We
have heard him testify as an observer; now let us hear him deal
historically and polemically with the doctrine in question. Quite
simply, in the final work of his old age, does the veteran tell of
the wide acclaim which at last has greeted his discovery of the
circulation--the most modern and revolutionary achievement of his
time. The contrast is startling when, in the same breath, with equal
simplicity he proceeds formally to identify his own latest view of
the significance of the circulating blood with a doctrine which had
been ancient in ancient times; a doctrine not only found in the Old
Testament, but held by Greek thinkers who were historic figures
even in the eyes of Aristotle. In his treatise On Generation Harvey
says:--
"I see that the admirable circulation of the blood which I
discovered long ago has proved satisfactory to nearly all, and
that so far no one has made any objection to it which greatly
calls for answer. Therefore, if I shall add the causes and
uses of the circulation and reveal other secrets of the blood,
showing how much it conduces to mortal happiness and to the
welfare of soul as well as body, that the blood be kept pure
and sweet by a right regimen, I truly believe that I shall do a
work as useful and grateful to philosophers and physicians as
it will be new; and that the following view will seem to nobody
so improbable and absurd as it formerly seemed to Aristotle,
viz.: that the blood, a domestic deity as it were, is the very
soul within the body, as Critias and others thought of old;
they 'believing that capacity for sensation is the most special
attribute of the soul, and exists because of the nature of the
blood.' By others again that which derives from its own nature
the power of causing motion was held to be the soul; as Thales,
Diogenes, Heraclitus, Alcmæon, and others believed.[297] It is
made plain, however, by very numerous signs that both sensation
and motion inhere in the blood in spite of Aristotle's[298]
denial."[299]
We have noted with Harvey the doctrine of Leviticus, which still
rules the procedure of the Jewish butcher; and as we look backward
to Athens across the centuries, we find Plato putting this question
into the mouth of Socrates: "Whether it be the blood with which
we think, or air, or fire, or none of these."[300] In Hellas
this doctrine had been well known before Plato, Socrates, or the
Hippocratic writers, one of whom we have found referring to it.
The Sicilian Greek Empedocles, a philosopher and physician born at
Acragas about 495 B.C., is said to have held, long before Aristotle,
that the heart is the part formed first in the embryo;[301] and
in a line of verse which has come down to us Empedocles said: "In
the blood about man's heart is his understanding."[302] Empedocles
is reported to have held to this because in the blood "are most
perfectly blended the elements of the parts,"[303] that is, earth,
water, air, and fire.
The accomplished and wicked Athenian Critias, to whom Harvey refers,
was that chief of the Thirty Tyrants who was slain in 403 B.C., four
years before Socrates drank the hemlock and nineteen years before
the birth of Aristotle. With the opinion of "Critias and others"
Harvey, as we have seen, identifies his own view that the soul is in
the blood. They held capacity for sensation to be the mark of soul
and to be due to the nature of the blood; and Harvey's statement
of these views is a literal quotation from the second chapter of
the first book of Aristotle's treatise On Soul, which Harvey cites.
This chapter is also the source of his summary and not quite exact
reference to those other ancients who, as he avers, held spontaneous
motor power to be the mark of soul--a power which Harvey unites in
the blood with capacity for sensation.[304]
In the aforesaid chapter of Aristotle's work On Soul this
philosopher had curtly reckoned among the "cruder" thinkers those
of his predecessors who, "like Critias," had held the soul to be
blood. Harvey notes the master's condemnation, but, as we have seen,
stoutly ranges himself with the condemned ancients and affirms that
sensation is inherent in the blood despite the master's denial.
It is strange to note how the London physician seems less modern,
for the moment, than the ancient philosopher of Athens. Aristotle,
like a man of to-day, treats the blood simply as the immediate
food of the tissues, noting expressly that it has "no feeling when
touched in any animal, just as the excrement in the belly has no
feeling."[305] Harvey deals as follows with this obvious truth in
dealing with the question whether the blood can properly be reckoned
a part of the body in the technical sense. He says:--
"At this time I will only say this: Even if we concede that
the blood does not feel, nevertheless, it does not follow that
it is not a part of a sensitive body and the principal part at
that."[306]
We do not know that Aristotle ever saw or noted in the dying auricle
the "undulation" by which Harvey was so much impressed; but we
have seen that, like Harvey, Aristotle treated of the development
of the early embryo within the hen's egg and that, like Harvey,
he laid special stress upon the red "leaping point." Aristotle
concluded that the heart is the first generated living part, that
it makes and will make throughout life the blood which it contains
and distributes. In the heart he fixed the focus of the innate heat
and, knowing nothing of the nervous system, he fixed in the heart
the seat of the soul also. Harvey came to the conclusion that the
blood is the first generated living part; that it has made the heart
which contains it and which keeps it circulating and which it will
nourish throughout life, as it will the other parts. In the blood
itself he placed the innate heat and, though he knew the nervous
system, he placed in the circulating blood the seat of the soul,
which animates every part.
"We conclude," he says, "that the blood lives and is nourished
of itself and in no wise depends upon any other bodily part
either prior to or more excellent than itself."[307]
Thus the rigorously proved and demonstrated circulation of the
blood was linked by its discoverer with the speculations of remote
antiquity.
As we have seen, the use of the circulation became to Harvey a
life-long subject of speculation, because this discovery had raised
questions which no man could answer before the finding of oxygen.
How obscure a problem Harvey found the functions of the blood to be,
is nowhere better indicated than where he says in his old age:--
"So with better right one might maintain that the blood is
equally the material of the body and its preserver, but not
merely its food. For it is well known that in animals that
perish of hunger, and also in men who waste away and die, there
is abundance of blood to be found in the vessels, even after
death."[308]
Is it the least part of Harvey's glory that his mind had cloven its
way through long-lived beliefs to a truth which he could demonstrate
but could not explain, and which seemed to other eminent men to be
no truth, because too senseless to be true?[309] When he finally
broke with the ancient master, Harvey could not be content with
sheer ignorance; and the same observations and experiments which
led him out of Aristotelian error misled him into error quite as
grave. As to the venerable doctrine regarding the seat of the soul,
which he at last embraced upon grounds now seen to be too slender,
was not this doctrine one with which the Harveian circulation
could harmonize well and which in turn could greatly glorify the
circulation? Let us pause, think, and read further.