40 HARVEY AND GALEN
Aristotle’s positive arguments for the heart being the centre of sensation and voluntary motion were partly the preconceived idea which I have just mentioned—partly his observations as a psychologist on the connexion of emotions with the heart, and also one fallacious anatomical observation. Seeing the chordae tendineae of the heart, he thought they were nerves and the source of all the nerves in the body. True, he did not distinguish between sinews and nerves, calling them all vetpa (xeura), but he must have regarded these structures as having what we now call motor nervous functions, since he thought them the origin of
Aristotle's belief that the brain was cold, indeed the coldest part of the body, which alone, according to his psychological theories, would make it impossible for the brain to be the seat of the sensory soul. The brain was, he thought, compounded of earth and water, the other elements, air and fire, not entering into its composition,
Aristotle regarded the heart as the seat of sensation and voluntary movement, partly from @ priori con- ceptions of the necessary connexion of the sensory soul with heat, and of heat with the blood, so that it must be located in the hottest part of the body ; partly from tracing the connexion of emotions with the heart, and partly from some ana- tomical fallacies alluded to above.
The first argument seems clearly established by the following passage from the De Partibus, which I quote fromDr.W.Ogle’s translation, p.72:—
‘The reason, then, why these two vessels [the vena cava and the aorta} coalesce into one centre and spring from one source is that the sensory soul is in all animals actually one; ...-and this oneness of the sensory soul determines a corresponding one- ness of the part in which it primarily abides. Where, however, the sen- sory soul is lodged, there also, and in
the selfsame place, must necessarily be the source of heat, and, again, where this is there also must be the source of the blood, seeing that it thence derives its warmth and flui- dity. Thus, then, in the oneness of the part in which is lodged the prime source of sensation and of heat is involved the oneness of the source in which the blood originates ; and this again explains why the blood-vessels have one common starting-point.’
It is curious how long Aristotle's idea that the brain was cold met with acceptance. Galen, indeed, contends that the only test of any- thing being hot or coldis that it is so to the touch (a criterion repudiated by the Aristotelians), and he states that the brain is rather moist than cold, hotter than some and colder than other parts of the body; while the heart was found in vivisections to be by far the hottest part (De Tempera- mentis, lib. ii). Piccolhomini, an anatomist of the sixteenth century, quoted by Harvey, placed one hand on the heart, the other on the brain, in a recently killed animal, and found them equally hot (Anatomuicae Prae- lectiones, 1586, p. 275). But we find Harvey, in his MS. Prelectiones of 1616, still teaching that the brain is cold.t
