I add the following supplementary remarks and illustrations.
Nearly all that is necessary to establish the first part of this thesis has already been brought forward in the preceding chapter, for in the necessity of sleep, in the alterations that arise from age, and in the differences of the anatomical conformation, it was proved that the intellect is of a secondary nature, and depends absolutely upon a single organ, the brain, whose function it is, just as grasping is the function of the hand; that it is therefore physical, like digestion, not metaphysical, like the will. As good digestion requires a healthy, strong stomach, as athletic power requires muscular sinewy arms, so extraordinary intelligence requires an unusually developed, beautifully formed brain of exquisitely fine texture and animated by a vigorous pulse. The nature of the will, on the contrary, is dependent upon no organ, and can be prognosticated from none. The greatest error in Gall's phrenology is that he assigns organs of the brain for moral qualities also. Injuries to the head, with loss of brain substance, affect the intellect as a rule very disadvantageously: they result in complete or partial imbecility or forgetfulness of language, permanent or temporary, yet sometimes only of one language out of several which were known, also in the loss of other knowledge possessed, &c., &c. On the other hand, we never read that after a misfortune of this kind the character has undergone a change, that the man has perhaps become morally worse or better, or has lost certain inclinations or passions, or assumed new ones; never. For the will has not its seat in the brain, and moreover, as that which is metaphysical, it is the prius of the brain, as of the whole body, and therefore cannot be altered by injuries of the brain. According to an experiment made by Spallanzani and repeated by Voltaire,[1] a
- ↑ Spallanzani, Risultati di esperienze sopra la riproduzione della testa nelle lumache terrestri: in the Memorie di matematica e fisica della Società Italiana, Tom. i. p. 581. Voltaire, Les colimaçons du révérend père l'escarbotier.
