products of the fertilization of nature by the human mind; but the record is dark, and the infant was cast out like Israel in the chapter of Isaiah.  But the high-water mark of mental achievement had not been reached by the great generation in which Hippocrates had labored.  Socrates had been dead sixteen years, and Plato was a man of forty-five, when far away in the north in the little town of Stagira, on the peninsula of Mount Athos in Macedoniawas, in 384 B.C., born a “man of men,” the one above all others to whom the phrase of Milton may be applied.  The child of an Asklepiad, Nicomachus, physician to the father of Philip, there must have been a rare conjunction of the planets at the birth of the great Stagirite.  In the first circle of the “Inferno,” Virgil leads Dante into a wonderful company, “star-seated” on the verdure (he says)—­the philosophic family looking with reverence on “the Master of those who know”—­il maestro di color che sanno.(28) And with justice has Aristotle been so regarded for these twenty-three centuries.  No man has ever swayed such an intellectual empire—­in logic, metaphysics, rhetoric, psychology, ethics, poetry, politics and natural history, in all a creator, and in all still a master.  The history of the human mind—­offers no parallel to his career.  As the creator of the sciences of comparative anatomy, systematic zoology, embryology, teratology, botany and physiology, his writings have an eternal interest.  They present an extraordinary accumulation of facts relating to the structure and functions of various parts of the body.  It is an unceasing wonder how one man, even with a school of devoted students, could have done so much.

     (28) The “Good collector of qualities,” Dioscorides,
     Hippocrates, Avicenna, Galen and Averroes were the medical
     members of the group.  Dante, Inferno, canto iv.

Dissection—­already practiced by Alcmaeon, Democritus, Diogenes and others—­was conducted on a large scale, but the human body was still taboo.  Aristotle confesses that the “inward parts of man are known least of all,” and he had never seen the human kidneys or uterus.  In his physiology, I can refer to but one point—­the pivotal question of the heart and blood vessels.  To Aristotle the heart was the central organ controlling the circulation, the seat of vitality, the source of the blood, the place in which it received its final elaboration and impregnation with animal heat.  The blood was contained in the heart and vessels as in a vase—­hence the use of the term “vessel.”  “From the heart the blood-vessels extend throughout the body as in the anatomical diagrams which are represented on the walls, for the parts lie round these because they are formed out of them."(29) The nutriment oozes through the blood vessels and the passages in each of the parts “like water in unbaked pottery.”  He did not recognize any distinction between arteries and veins, calling both plebes (Littre); the vena cave