More than thirty-two years earlier Harvey had written in his note-book the following words:-- "N.B. The lungs by their movement in subsiding propel blood from the arterial vein into the venous artery and thence into the left auricle."[270] When we review and ponder the foregoing delineations of the character of the movement of the blood, we may cease to wonder that Harvey did not recognize the simple hydraulic cause of the distention of the right auricle and felt obliged to seek a more recondite explanation thereof, finding this in an Aristotelian expansion of the hot blood. CHAPTER IX 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:--