is the great vessel, and the aorta the smaller; but both contain blood.  He did not use the word “arteria” (arthria) for either of them.  There was no movement from the heart to the vessels but the blood was incessantly drawn upon by the substance of the body and as unceasingly renewed by absorption of the products of digestion, the mesenteric vessels taking up nutriment very much as the plants take theirs by the roots from the soil.  From the lungs was absorbed the pneuma, or spiritus, which was conveyed to the heart by the pulmonary vessels—­one to the right, and one to the left side.  These vessels in the lungs, “through mutual contact” with the branches of the trachea, took in the pneuma.  A point of interest is that the windpipe, or trachea, is called “arteria,” both by Aristotle and by Hippocrates ("Anatomy,” Littre, VIII, 539).  It was the air-tube, disseminating the breath through the lungs.  We shall see in a few minutes how the term came to be applied to the arteries, as we know them.  The pulsation of the heart and arteries was regarded by Aristotle as a sort of ebullition in which the liquids were inflated by the vital or innate heat, the fires of which were cooled by the pneuma taken in by the lungs and carried to the heart by the pulmonary vessels.

     (29) De Generatione Animalium, Oxford translation, Bk.  II,
     Chap. 6, Works V, 743 a.

In Vol.  IV of Gomperz’ “Greek Thinkers,” you will find an admirable discussion on Aristotle as an investigator of nature, and those of you who wish to study his natural history works more closely may do so easily—­in the new translation which is in process of publication by the Clarendon Press, Oxford.  At the end of the chapter “De Respiratione” in the “Parva Naturalia” (Oxford edition, 1908), we have Aristotle’s attitude towards medicine expressed in a way worthy of a son of the profession: 

“But health and disease also claim the attention of the scientist, and not merely of the physician, in so far as an account of their causes is concerned.  The extent to which these two differ and investigate diverse provinces must not escape us, since facts show that their inquiries are, at least to a certain extent, conterminous.  For physicians of culture and refinement make some mention of natural science, and claim to derive their principles from it, while the most accomplished investigators into nature generally push their studies so far as to conclude with an account of medical principles.” (Works, iii,480 b.)

Theophrastus, a student of Aristotle and his successor, created the science of botany and made possible the pharmacologists of a few centuries later.  Some of you doubtless know him in another guise—­as the author of the golden booklet on “Characters,” in which “the most eminent botanist of antiquity observes the doings of men with the keen and unerring vision of a natural historian” (Gomperz).  In the Hippocratic writings, there are mentioned 236