"It is most exceeding full of contained blood, as no other viscus is. Wherefore Aristotle [holds] against the physicians that the origin of the blood is not in the liver but in the heart, because in the liver there is no blood outside the veins. Rather is the blood the origin of both, as I have seen."[161]
In a third passage Harvey says of the heart that its
"temperature is exceeding hot, inasmuch as it is exceeding full of blood."[162]
In a fourth passage of the lecture notes which bears upon the primacy of the blood we may read:—
"1. [The heart] is the most principal part of all, not because of itself,[163] for its flesh is more fibrous and harder and colder than the liver, but because of the abundance of blood and spirits in the ventricles.
"1. Whence the fount of the entire heat.
"Whence the auricles pulsate, after removal of the heart, because of the multitudinous blood.[164]
"2. Nor is [the heart] the principal part because of its origin: for I believe that the ventricles (which in the fœtus are both united as in fishes) are made out of a drop of blood which is in the egg; and that the heart, together with the rest [of the parts] all sprout[165] simultaneously, as [occurs] in an ear of corn, from an imperceptible size. Is there only a drop of blood in the auricles whence bestowing heat upon all parts, receiving from none, it is the citadel and domicile of the heat, the household shrine[166] of that edifice, fowntayn conduit hed."[167]
More than eleven years after the making of his lecture notes Harvey, at the age of fifty, published his treatise of 1628; and later, after keeping silence for more than twenty years, he published together the two Exercises addressed to Riolanus. During these twenty years and more the blood must have been rising and the heart declining, in Harvey's esteem, as ruling powers in the body; for at the end of that time more than thirty-two years after the jotting down of the statements and varied conjectures of his lecture notes, he formally throws over Aristotle's primacy of the heart, in a passage near the close of the second Exercise to Riolanus. Of this passage the following is a part. Referring to certain opinions, mainly Aristotelian, regarding the heart and blood, Harvey says:—
"To speak openly, I do not believe that those things are so in the sense commonly received; and my opinion is inclined in the direction aforesaid by much which is visible in the generation of the parts, but which is not convenient to set down here. Soon, perhaps, I shall make public things even more wonderful and destined to cast even greater light upon natural philosophy.
"For the present I will only say and set forth without demonstration—by good leave of the learned and with due respect to the ancients—that the heart, as the beginning, author, source, and origin of everything in the body and the first cause of life, should be held to include the veins and all the arteries and also the contained blood; just as the brain, including all its nerves and sensory organs and spinal marrow, is the one adequate organ of sensation, as the phrase is. If by the word 'heart,' however, only the body of the heart be meant with its ventricles and auricles, I do not believe that it is the manufacturer of the blood; nor that the blood possesses vigor, faculty, reason,[168] motion, or heat, as the gift of the heart."[169]
In the second year after that of the Exercises to Riolanus Harvey's final publication, his treatise On Generation with appended essays, was given to the world, not long before his seventy-third birthday. During how many years this work had been in preparation we do not know; but it is avowedly based upon the views of Aristotle, whom Harvey styles his "dux"—his leader—as regards the subject of this treatise.[170] In it, to be sure, the ancient master is often weighed in the balance and found wanting by Harvey, who even questions whether Aristotle had seen for himself what he "narrates as to the generation of the chick," or "had accepted it from some expert."[171] Nevertheless, it is with the doctrines of Aristotle that Harvey incessantly compares the results of observation. Here the veteran records anew his denial of the Aristotelian primacy of the heart, and records as well his final emphatic assertion of the primacy of the blood. In regard to these matters it is interesting to note the various grades of expression which appear to mirror in this single work the various phases of Harvey's thought.
In the following florid passage doubt of the primacy of the heart seems hardly even hinted at. Harvey says:—