THE CIRCULATION AND THE ARISTOTELIAN PRIMACY OF THE HEART
It has been stated already that the first announcement of the
circulation is to be found in Harvey's lecture notes. The following
is the text of the memorable passage in question, which I have
translated from Harvey's Latin. He says:--
"It is proved by the structure of the heart that the blood is
perpetually transferred through the lungs into the aorta, as
by two clacks of a water-bellows to rayse water. It is proved
by the ligature that there is a transit of the blood from
the arteries to the veins; whereby it is demonstrated that a
perpetual movement of the blood in a circle is brought about by
the beat of the heart. Is this for the sake of nutrition, or of
the better preservation of the blood and members by infusion of
heat, the blood in turn being cooled by heating the members and
heated by the heart?"[106]
The words "as by two clacks of a water-bellows to rayse water"
are Harvey's own racy English, embedded in his Latin text. The
"ligature" is the flat band which is tied about the upper arm when
bleeding from a vein is to be practised at the bend of the elbow.
The Hippocratic physicians called this band a "_taenia_,"[107] and
even in their day it was known to hasten the flow of blood from
the opened vein when applied as above stated, but yet to check the
flow if tied too tight. This clinical observation had awaited
a rational explanation for more than nineteen centuries.[108]
[Illustration:
Page 80, right, of William Harvey's _Prelectiones Anatomiæ
Universalis_, or Lecture Notes of 1616. The passage contains the
first recorded mention of the movement of the blood in a circle.]
[Illustration:
WH constat per fabricam cordis sanguinem
per pulmones in Aortam perpetuo
transferri, as by two clacks of a
water bellows to rayse water
constat per ligaturam transitum sanguinis
ab arterijs ad venas
vnde Δ perpetuum sanguinis motum
in circulo fieri pulsu cordis
An? hoc gratia Nutritionis
an magis Conservationis sanguinis
et Membrorum per Infusionem calidam
vicissimque sanguis Calefaciens
membra frigifactum a Corde
Calefit
Transcript of the preceding page.]
Our most immediate interest in the foregoing passage lies in this:
that on the very same page, with the few clear simple words which
tell for the first time of Harvey's facts and proofs, he has briefly
written down conjectures as to the meaning of the circulation.
These are as strikingly put as certain jottings are obscure which
deal on a neighboring page with some possible meanings of the
heart-beat.[109] In neither group of conjectures do the functions of
the lungs play a part; but the discoverer asks himself whether it
be not to revisit the heat of the heart that the whole mass of the
blood circles back to the chest in its Harveian course! More than
thirty-two years after the date of Harvey's note-book Harvey wrote
to Riolanus:--
"There are some who consider that as no impulsion of nutriment
is required for the nutrition of plants, their particles
attracting little by little whatever they need to replace what
they have lost, so in animals there is no need of any impulsion,
the vegetative faculty in both working alike. But there is a
difference. In animals a perpetual flow of warmth is required to
cherish the members, to keep them alive by the aid of vivifying
heat, and to restore parts injured from without. It is not
merely nutrition that needs to be provided for."[110]
In the first Exercise to Riolanus Harvey had touched also upon the
use of the circulation, interweaving this doctrine of heat with the
doctrine of respiration as he then held it, in a passage the last
part of which I have quoted already. Quoted more fully he says:--
"And this, indeed, is the principal use and end of the
circulation, for which the blood revolves with perpetual
influence in its ceaseless course and is driven along its
circuit: namely, that all the parts in dependence upon the
blood may be kept alive by the primary innate heat and in their
state of vital and vegetative being, and may perform all their
functions; whilst, to use the language of physiologists, they
are sustained and actuated by the inflowing heat and vital
spirits. Thus by the aid of two extremes, viz.: cold and heat,
is the temperature of the animal body retained at its mean. For
as the air inspired tempers the too great heat of the blood in
the lungs and center of the body and effects the expulsion of
suffocating fumes, so in its turn does the hot blood, thrown
through the arteries into the entire body, cherish and nourish
and keep alive all the extremities, preventing extinction due to
the power of external cold."[111]
"The innate fire is not in the right ventricle," a Hippocratic
author had written, who had written also that the wall of the
left ventricle is dense, to guard the strength of the heat.[112]
Aristotle, too, had placed in the heart the "origin" of the "natural
innate heat";[113] had likened the heart to "the hearth on which
shall lie the natural kindling, well protected also, as being the
acropolis of the body."[114] At a later day Galen had affirmed the
same doctrine.[115]
Let us turn now to the famous treatise of 1628, published twelve
years after the note-book had been written. In the chapter in which
Harvey says "I tremble lest I have mankind at large for my enemies"
and then publishes and names the circulation,--in this chapter,
before passing to his proofs, he published the following words
which resound in a way very different from the simplicity of the
note-book:--
"So probably it may come to pass in the body through the
movement of the blood that all the parts are nourished,
cherished, quickened, by the hotter, perfected, vaporous,
spirituous, and, so to speak, alimentive blood; that the blood,
on the other hand, is cooled, coagulated, and rendered, as it
were, effete in the parts; whence it returns to its origin,
namely, the heart, as to its fountain, or the hearth of the
body, to regain perfection. There by the potent and fervid
natural heat, a treasury of life, as it were, the blood is
liquefied anew and becomes pregnant with spirits and, so to
speak, with balsam. Thence the blood is distributed again; and
all this depends upon the motion and pulsation of the heart.
"The heart, therefore, is the origin of life and the sun of the
microcosm, even as the sun in his turn might well be called the
heart of the world; by the vigor and pulsation of the heart
the blood is moved, perfected, quickened, and delivered from
corruption and thickening; and the function of nourishing,
cherishing, quickening the entire body is performed by that
intimate hearth, the heart, the foundation of life, the author
of all. But of these matters more conveniently when I shall
speculate as to the final cause of motion such as this."[116]
Upon this florid passage follow the classic six chapters which bring
forward with such power and calm the proofs of the circulation.
These are succeeded in their turn by words which echo their
sobriety, as follows:--
"It will not be beside the question to show also from certain
familiar reasonings, that the circulation is both convenient and
necessary. In the first place, since death is corruption from
deficiency of heat[117] and since all living things are warm,
all dying things cold, the heat requires a seat and origin, a
home and hearth, as it were, in which the tinder of nature,
the first beginning of the innate fire, may be contained and
preserved; a place from which, as from their origin, heat and
life may flow out into all the parts, whence nutriment may come
and upon which concoction and nutrition and all quickening may
depend. That this place is the heart, that this is the origin of
life as aforesaid, I should hope that none would doubt.
"Hence the blood has need of motion, of motion such that it may
return to the heart; for, if sent to the outer parts of the
body, far from its source,[118] and left unmoved, it would
become coagulated. Heat and spirits are seen to be generated
and preserved in all by motion, to vanish if quiet supervene.
Therefore, the blood, thickened or stiffened by the cold of the
extremities and of the ambient [air] and destitute of spirits,
as in the dead, must needs return to its source and origin in
order to keep itself whole, to seek thence and repair again its
heat and spirits."...[119]
"Moreover," Harvey says, a page farther on, "since all animals
live by nutriment concocted in their interior, it is necessary
that the concoction and distribution thereof be perfect; and,
further, that a place and receptacle exist where the nutriment
may be perfected and whence it may be led off to the several
members. Now this place is the heart, for it alone of all the
parts contains blood for the public use in its cavities, the
auricles and ventricles, as in cisterns and storehouse; not
merely blood for its private use in the coronary vein and
artery."[120]
In the next chapter we obtain glimpses of the pathological relations
of this physiology. Harvey brings forward tertian fever as a case in
point, explaining that the febrile paroxysm is produced when
"the preternatural heat which has been kindled in the heart is
diffused throughout the entire body by way of the arteries,
together with the morbific matter which thus is evaporated and
dissolved by nature."[121]
As a student of the Greek science reads the foregoing passages,
he clearly sees that the new wine of the circulating blood is
poured into the old bottles of the Aristotelian physiology; and
Harvey tells us so himself, in the last chapter of his most famous
treatise. He says:--
"No less should we agree with Aristotle as to the sovereignty of
the heart, in dealing with the following and similar questions:
Does it receive motion and sensation from the brain, blood
from the liver; or is it the origin of the veins and of the
blood? For they who try to refute him leave out, or do not
grasp, the main argument, which is that the heart is the first
part to exist and has in it blood, life, sensation, motion,
before the brain or the liver has been made or is clearly to
be distinguished, or at least before either can perform any
function. So the heart with its own proper organs constructed
for motion--as it were, an internal animal--is the earlier
formed; and, this being the first made part, it is the will of
nature that thereafter the entire animal be made, nourished,
preserved, perfected by the heart to be its achievement and
abode. The heart is governor everywhere, like the chief in
a commonwealth with whom is lodged the first and highest
authority. In an animal all power is derived from and depends
upon the heart as its origin and foundation."[122]
The main argument, which is that the heart is the first part to
exist, is simply the argument from the development of the embryo
in the hen's egg. The study of this development day by day had
been recommended by one of the Hippocratic writers,[123] and
Aristotle had laid stress upon the changes in the embryo during
incubation.[124] Harvey, in his turn, had studied them carefully.
The ancients could have made their observations only with the naked
eye, but Harvey had the aid of a simple lens, though of nothing
approaching in power to a microscope.[125] In the treatise of 1628
he speaks as follows of what he thus observed:--
"If you turn to the formation of the chick in the egg, the first
thing to exist therein, as I have said, is a mere vesicle, or
auricle, or pulsating drop of blood. Afterward, when growth has
gone on, the heart is completed.... In a hen's egg after four
or five days of incubation I have shown the visible presence of
the rudiment of the chick in the form of a little cloud; in an
egg, that is, which had been immersed in clear tepid water after
removal of the shell. In the middle of the aforesaid little
cloud there was a palpitating bloody point, so fine that in
contracting it disappeared and became invisible, but reappeared
on its relaxation, looking like the point of a needle, and of
a ruddy color; so that being now visible and now invisible, as
though now existent and now non-existent, it evinced palpitation
and the beginning of life."[126]
In the same treatise Harvey promises to publish more observations
"on the formation of the fœtus, where numerous problems of
the following order can find a place: Why should this point be
made or perfected earlier, that later? As regards the dominance
of the members: Which part is the cause of the other? There are
very many problems connected with the heart, such as: Why should
it be the first thing (as Aristotle says in his third book on
the parts of animals)[127] to acquire consistency, and be seen
possessed of life, motion, and sensation, before anything has
been perfected in the rest of the body? And in like manner
regarding the blood: Why is it before all, and how possessed
of the beginnings[128] of life and of the animal, and of the
craving to move and be impelled hither and thither, to which end
the heart would seem to have been made?"[129]
In Harvey's celebrated treatise, despite various frank questionings
by the way, such as that just quoted about the blood, he so
frankly follows in the footsteps of "the master of them that know"
that Aristotle need not be cited at length to prove the fact. To
Aristotle are largely due Harvey's references to the heart as
the central source of indispensable vital heat; his references
to aliment perfected in the heart; his blending of psychological
doctrines with the doctrine of the movement of the blood. Therefore,
a brief account of how this became possible will be germane.
When an ancient observer looked with the naked eye at the very early
embryo of the fowl, he distinguished at first only a blood-red
point, which pulsated, or "leapt." This Aristotle judged to be the
heart, containing blood before any blood-vessel had shown itself
and before blood was visible in any other part. Very soon, however,
two vessels containing blood were seen, according to him, to extend
from the rudimentary heart toward the periphery. From these and
other considerations Aristotle inferred that both the blood and all
its containing vessels owe their first origin to the heart; and that
throughout life the liquid made elsewhere from the food enters the
heart, there to be perfected into blood by the action of the vital
innate heat, of which, as we have seen, he held the fiery central
hearth to be within the heart. Naturally, therefore, he believed the
blood not to be hot of itself, but to acquire its vivifying heat at
the heart, the pulsation of which he held to be caused directly by
the seething of the blood within. When thus perfected and charged
with heat the blood, according to him, is distributed from the heart
through the vena cava as well as the aorta. These great vessels and
their subdivisions Aristotle distinguished anatomically; but he
made no serious physiological distinction between what we call the
veins and the arteries, and, himself, applied the word "artery" to
the windpipe only. As to the cavities and contents of the heart,
even as to the number of its cavities, he had obscure, complex, and
erroneous ideas, and of the valves he knew nothing. He recognized
no essential differences between the matters distributed by way of
the vena cava and by way of the aorta, all being, alike, one thing,
blood; though the blood was hotter or cooler, thinner or thicker,
purer or cruder, in different regions or parts of the body, in
different sets of vessels, in different cavities of the heart, or at
different times in the same place.
We have seen already that, in the genuine works of Aristotle, there
is no sign that what we call the tissues of the adult require or
receive a derivative of the air, whether crudely mingled with the
blood in the earlier Hippocratic way, or separate in Erasistratean
fashion, or in the form of such "spirituous blood" as Galen
afterward accepted. We have seen that the air which Aristotle
believed to enter the heart for cooling purposes, cannot be traced
beyond it; that whatever spirits may exist in the body for him,
would seem to be either of the nature of vapor produced within the
body itself, or of a nature quite indeterminate.[130]
The living egg of the hen has had a vast deal to do with the history
of psychology as well as of physiology. It is partly owing to what
Aristotle believed to go on in the egg that we speak to-day of
good hearts and bad hearts--even of sweethearts. Aristotle knew
nothing of the nerves, and, therefore, could reasonably fail to find
conclusive evidence that the brain and spinal cord had to do with
what we call nervous functions. So he fell back upon a doctrine at
least as old as the Iliad,[131] and made a psychological center of
the heart. This being proved, for Aristotle, largely by its demeanor
in the early embryo, to be the life-long source of the nutritive
blood; and being, for him, the central hearth of the heat by means
of which the blood is perfected and warmed; he held it a matter of
necessity that in the heart should dwell the so-called "nutritive
soul"; that is, the faculty which uses as its most immediate
instrument the "innate," "natural," "vital," "psychical," heat, to
bring about nutrition, growth, and generation. He says:--
"It is impossible that the other faculties of the soul should
exist without the nutritive, or these without the natural fire;
for in this has nature set that faculty aglow."[132]
Dealing with these other faculties, he sees that there must be an
organ where the results of sight, hearing, and the other senses, are
compared; and deliberately discussing and rejecting the claims made
for the brain he makes the heart this "common sense-organ of all the
sense-organs," as he styles it. He says:--
"If in all the creatures the seat of life is in this part, it is
clear that here also must the origin of sensation be; for we say
that the body has life because it is an animal, but we say that
it is animal because it has sensation."[133]
Less hollow rings the argument in the modern ear, when the ancient
thinker bases it on conclusions drawn from observation. We learn
from him that only those parts are sensitive which contain blood, as
opposed to hair and nails, or even to the blood, if taken by itself.
We learn, therefore, that as the heart of the embryo is the first
part to contain blood, it is the first part to be sensitive and
hence is the central source of sensation. Moreover, Aristotle, like
Plato,[134] knowing nothing of the nerves, judges the blood-vessels
to be sensory paths; and blood-vessels connect, not only the
sensitive flesh, but all the more special sense-organs with the
heart. Such is the outline of the reasons why Aristotle held the
heart to be the lifelong seat, not only of the "nutritive soul," but
of the "sensory soul" as well.
Pain, pleasure, and desire would naturally dwell beside sensation
in the heart, which Aristotle held to be obviously the seat of the
emotions, as proved by its palpitation when they are stirred.
Moreover, it is desire, seated in the heart, which incites to
action, to motion, movement thus resulting from sensation; and,
in general, "the movements" of every sense both begin and end at
the heart; the word here translated "movement"[135] being used, in
the technical diction of Aristotle, to include not only the "molar
motion" of modern parlance, but also subtle forms of change of
state. Further, in the early embryo the heart itself is plainly the
first part which possesses motion; it visibly taking the lead in
this, moving "as though itself an animal." The pulsating movements
of the heart are the direct effects of the seething and vaporization
within it; while, in the respiratory movements, the chest wall is
pushed out by an expansion due to the vital heat, whose cardiac
hearth the lungs inclose, and then follows inward a contraction due
to the cooling air which has been drawn into the expanding lungs.
As the bodily movements, in general, are "brought about by drawing
and slackening" and originate at the heart, it is appropriate that
the heart contains tendinous structures[136] within itself; "for
it needs the service and strength" of such.[137] It is too, in a
sense, the origin of the discontinuous tendinous and ligamentous
structures of the body. Aristotle's doctrine of the heart as the
source of motion seems especially vague. But, hardy thinker though
he was, he scarcely could be definite on this subject, even in
speculation. He knew that heat expands and cold contracts; he
recognized the force which, as he believed, confined or compressed
vapor exerts in living bodies, not only in health but in disease;
and he knew the strength imparted to bodily effort by holding the
breath. His genuine writings, however, bring forward no _modus
operandi_, except in the case of respiration and of the movements
of the heart itself. We are given no inkling as to how the tendons
are normally drawn and slackened in obedience to the will, for the
true function of muscle was unknown to Aristotle (Harvey to the
contrary notwithstanding),[138] and the blood-vessels were the
only continuous special paths between center and periphery which
Aristotle could make out. In his time, as we have seen, the nerves
had not been distinguished, even anatomically, from the bands and
cords of the ligaments and tendons.
So, for Aristotle, the nutritive, sensory, and motor faculties, the
desires and emotions, in short all the souls or parts of the soul
(to use the ancient phraseology) that are not the most exalted,
dwell in fire within the heart, suitably and honorably placed at the
central "acropolis." To the divine mind of man, on the other hand,
he does not assign a definite special dwelling-place within the body.
Harvey differed often and widely from Aristotle. Yet even in
his old age he wrote: "The authority of Aristotle has always
such weight with me that I never think of differing from him
inconsiderately."[139] Cannot one fancy, may not one conjecture,
that in the eyes of the discoverer of the circulation his great
discovery, fundamental, new, and original, as he rightly claimed it
to be, may at times have seemed to constitute a thorough correcting
and filling in of a rough sketch dashed off at the Lyceum? Let us
see.
Aristotle had no conception of anything resembling a circulation of
the blood, nor any definite mechanical ideas as to its movement.
While the vena cava as well as the aorta received blood from his
valveless heart and yielded it to the body at large, blood ebbed
back to the heart during sleep, and the warm nutrient liquid which
the vena cava and the aorta yielded to the tissues had previously
entered the heart continuously but in an imperfect state through
both of these great vessels, to go forth again through both,
perfected into blood and heated, with no perplexing differences of
color noted between that in the great vein and that in the aorta.
The relations between the food, the blood, the heart, and the body
at large, though recognized to be complex, may well have presented
themselves to Aristotle with something of the vagueness with which
the relations between the food, the liquids, the contractile
vacuole, and the living substance of a protozoön, present themselves
to us. If the heart, retaining its Aristotelian powers, were found
to receive the blood imperfect or impaired, but to receive it by the
veins only, and to send it out, but only by the arteries, warmed and
perfected or restored to perfection at its Aristotelian source; what
have we but the systemic part of the circulation, as it may have
pictured itself sometimes to Harvey?[140]