Harvey's Views on the Use of the Circulation of the Blood

by John Green Curtis

"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]