SECT. VII.] EXISTENCE OF ANIMAL SPIRITS DENIED. 879 



the nerves acted as solid tense-cords, alternately contracting 

 and relaxing, or only oscillating. But it was easy to demon- 

 strate to these, that the nerves are soft, pulpy, and not tense- 

 cords, and therefore unsuitable to the functions assigned to 

 them : this hypothesis being rejected, the authority of the 

 other, as to the animal spirits, increased. In the next place, 

 opponents of the animal spirits were found in the Stahlians, who 

 maintained that all the functions of the nerves depended directly 

 on the soul, and who rejected the animal spirits (whose exist- 

 ence was not proved) as useless. But the defenders of the 

 animal spirits silenced these opponents also, not by proving the 

 existence of the spirits, but because they overturned the foun- 

 dations of the Stahlian doctrines, which, it appears to me, Haller 

 especially accomplished. After this second victory over the op- 

 ponents of the animal spirits, some distinguished men of the 

 mechanical school attempted to prove their existence by various 

 and far-fetched arguments ; the principal were Boerhaave, 

 Haller, and Tissot, the latter plainly endeavouring to establish 

 the hypothesis as a truth. Notwithstanding the authority of 

 these great names, the love of truth excited distinguished men, 

 who advanced doubts as to this hypothesis of the animal spirits, 

 and who showed that the arguments adduced in its favour 

 proved nothing when carefully analysed, and that the whole 

 hypothesis was altogether devoid of truth. Of these the illus- 

 trious Caldani, so highly esteemed by Haller, on account of 

 his great merit in medical art, led the way ; and whose argu- 

 ments have, I think, the greater weight, because, although a 

 most dear friend to Haller, yet led by the love of truth, he did 

 not hesitate, in this case, to think and act in opposition to him. 

 Afterwards Metzger,^ Azzoguidi,^ Mayer,^ Michelitz,^ Marzari,^ 

 and Fiorati, in the notes to his Italian edition of ^ Tissot on 

 the Nerves,' joined their arguments to undermine and entirely 

 overthrow the hypothesis; and if we consider these with a 

 mind free from prejudices, we cannot but forget the hypothesis 

 as we would a dream, and be excited to inquire after truth in 

 another way than through hypotheses and conjectures. 



* Adversar. Med. 

 « Instit. Med. 



^ Abhand. vom Gehirn, Ruckenmark, und Ursprung der Nerven. 



* Scrutin. hypoth. Spirit. Anim. 



* Dissertazioni Accadem. delle Ipotesi, &c. 



