"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."[191]
In his last publication, of 1651, we have read:—
"So far as can be discerned by accurate inspection, the blood is made before the leaping point is formed, and the blood is endowed with vital heat before it is set in motion by pulsation; and further, as pulsation is begun in and by the blood, so at last it ends in the blood at the final instant of death."[192]
Harvey's own words in the foregoing two passages effectively sum up both the nature of his doctrine that the blood is the first part of the body to live, and the nature of his evidence. But the words of the second passage foreshadow a closely related doctrine, advanced and held by him on the evidence of observation, viz.: that the blood, being the first part to live, is also the last part of the body to die. That the first part to live is always the last to die, is a doctrine set forth by Aristotle. This, Harvey seems to accept without question and to apply upon proper evidence to the blood; as he accepts and warmly upholds the ancient master's doctrine that there is a primacy of the body. The results of observation have forced Harvey to transfer this primacy from the heart to the blood, but it is the Aristotelian primacy still. Presently he shall show us that the blood is not only the first part to live, but the last to die. Before he does so, however, let Aristotle speak for himself, saying briefly:—
"The point[193] of origin [of the rest of the body] is the first thing generated. The point of origin in the animals which possess blood is the heart; in the rest, the analogue thereof, as I have often said. Moreover, the fact that the heart is the first thing generated is evident, not only to the senses, but from its death.[194] For therein life ceases the last; and in all cases the last generated is the first to make an end, the first generated, the last to make an end; nature, as it were, doubling back and returning upon her point of origin whence she came.[195] For generation is the change from not being to being; destruction is the reverse change, from being to not being."[196]
Aristotle does not tell us why "in all cases ... the first generated" is "the last to make an end," and vice versa. Let it suffice that Harvey accepts this sweeping doctrine. Now let him complete his evidence in favor of the primacy of the blood by showing that the blood is not only the first part to live and to live tenaciously, but the last part to die.
In a passage of the treatise On the Motion of the Heart and Blood, we have already read Harvey's promise to publish observations
"on the formation of the fœtus, where numerous problems of the following order can find a place: Why should this part 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]
That Harvey should have printed this passage in 1628, in the same work with his repeated eulogies of the Aristotelian heart, shows that the idea of the possible primacy of the blood must have been in his mind early. It was, indeed, so from the jotting down of his private notes of 1616, to the publication of the Exercises to Riolanus in 1649 and the treatise On Generation in 1651. The same mental attitude is revealed, perhaps more strongly, in the following passage of an earlier chapter of Harvey's treatise of 1628. Here we come upon the thought that it may be the blood, and neither ventricle nor auricle, which is the last to die. Harvey says:—