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

by John Green Curtis

According to Harvey the horse of battle of his criticized predecessors was the argument stated by him as follows: "That nothing composed of the elements can work beyond the powers of these, unless it be associated at the same time with another body and that more divine; and ... therefore, that the spirits aforesaid consist in part of the elements, in part of some ethereal and celestial substance."[351] The "spirits aforesaid" are held to be one and the same with the innate heat and reside in the blood. Aristotle had written, we remember: "The virtue or potency of every soul seems to be associated with a body other than the so-called elements and more divine,"[352] viz.: the generative seminal heat, which is not fire but an analogue of the ether. It would seem fairly probable that largely from this doctrine of Aristotle was developed the doctrine about the "powers of the elements" which Harvey sets forth in his polemic. Nothing can be more emphatic than his disagreement with the advocates of this doctrine. "Such persons," he says, "seem to me to have drawn their conclusions ill. For you shall find scarcely any elemental body which, when in action, will not exceed its own proper powers."[353] On the same page with this sweeping statement we find it supported by the following very simple line of thought:—

"All natural bodies present themselves in a double relation, to wit: according as they are reckoned with apart and comprehended within the circuit of their own proper nature, or according as they are the instruments of some nobler and superior authority. For, as to their own proper powers, there is no doubt that all things which are subject to generation and corruption derive their origin from the elements, and work according to the standard thereof. In so far, however, as all things so subject are instruments of a more excellent agent and are regulated thereby, their works do not proceed from their own proper nature but from the rule of that other; and, consequently, they seem to be associated with another and more divine body and to exceed the powers of the elements."[354]

In the very next Exercise, however, that On the Primitive Moisture, the last Exercise of Harvey's treatise On Generation, we come suddenly upon a reason why "the powers of the elements" must have seemed to him something to be treated rather as a convenient form of words than as a serious doctrine, despite his respectful argument just quoted. Speaking of the "primitive moisture," the great observer says that he sees in the hen's egg that out of that "crystalline colliquament," that "simplest body" alone, all the parts of the embryo are made and increased;[355] and proceeds bluntly to question the reality of the elements, "namely, the fire, air, water, and earth of Empedocles and Aristotle; or the salt, sulphur, and mercury of the chemists; or the atoms of Democritus."[356] Harvey says:—

"Therefore, the so-called elements do not exist prior to whatever is generated or arises; but rather are subsequent thereto, being remains rather than origins. Not even Aristotle himself, nor any one else, has ever demonstrated that elements exist separately in nature, or give rise to bodies which consist of parts similar one to another."[357]

Almost immediately after this tug at the foundations of the Aristotelian universe, Harvey brings his treatise On Generation to an end.

The admirable feature of Harvey's brief last-published discussion of the circulating blood is this, that the aged veteran ever strikes vigorous blows for observation, for the use of the senses, in the search for truth. But we have seen already that by his arm, as by another's, the blows are delivered both for better and for worse. Rightly does he drive out of court the spirits "ethereal and elemental" which no man can demonstrate. Wrongly does he discredit the real complexity of that humor, to the eye so simple and crystal-clear, out of which he believes all the diverse parts of the living bird to be developed. In Harvey's present polemic we find no new appeal to nature; he vindicates the justice of his former appeals and maintains with vigor the doctrines already familiar to us, that the blood is the principal part of the body, is itself the innate heat, and is the seat of the soul. This relation of blood and soul he reaffirms very impressively in this, his final public utterance; a most important passage of which, about the presence of the soul in the blood, has been embodied in the chapter on that subject of the present paper.[358]

But evidently the main purpose of his polemical Exercise on the Innate Heat is to cast out of the blood the futile spirits which obscure the real relation of that heat to the circulating blood; and so to defend the thesis best set forth in the following words of his own:—

"In truth, the blood alone is the innate warmth, or the first born psychical heat; as is proved excellently well by our observations of the generation of animals, especially of the chick in the egg; so that it were superfluous to multiply entities....[359] What need, then, is there, say I, of that foreign guest, ethereal heat, since all can be accomplished by the blood, even as by it?"[360]

Harvey has expelled from the blood the mythical spirits which had stood in the way of the direct identification of the blood with the innate heat. But how does he interpret the famous words of Aristotle which he quotes, and declares not to have been "rightly interpreted" by the champions of ethereal spirits? When we seek an answer to this question, we do not find the veteran discoverer at his best. The ancient philosopher surely would have been as much surprised at Harvey's interpretation of his words as at any use of them made by Scaliger or Fernelius. We have seen that Harvey follows up his quotation from Aristotle by promptly applying its language, literally or by paraphrase, to the innate heat and the blood.[361] Emphatic are the words which immediately follow the words of Aristotle. Harvey says:—

"I, too, would say the same, for my part, of the innate heat and the blood, to wit: that it is not fire and does not take its origin from fire, but is associated with another body and that more divine."