586 LEADING DOCTRINES 



phers, who have equally confounded cause and 

 effect. Sir Isaac Newton himself has fallen into 

 a like error, when he says that " animal motion 

 may be performed by vibrations of the (Ether, excited 

 in the brain by the power of the will." For how 

 can the brain will, unless previously vitalized ? or 

 if the will depend on the activity of the brain, 

 how can it be the cause of its supposed vibrations, 

 or of any other species of cerebral motion ? Is it 

 not manifest, that sensation, memory, and voli- 

 tion, are mere modes of action of the living prin- 

 ciple, exerted through the nervous system ? For 

 when life ceases, they are wholly extinguished ; 

 therefore, like the mind itself, cannot be regarded 

 as material entities (as they have neither exten- 

 sion, solidity, nor any other properties of tan- 

 gible matter,) but as effects of the same cause 

 that generates attraction, repulsion, vibration, 

 chemical affinity, and all the motions of passive 

 matter. 



But it was reserved for the celebrated Cullen 

 to erect on the ruins of nearly all that was true 

 in the medical doctrines of antiquity, one of the 

 most visionary systems ever invented by the sub- 

 tilizing genius of man ; and which has exerted an 

 astonishing influence in retarding the progress of 

 sound practical knowledge. Although he admits 

 that all the phenomena of health and disease 

 must be referred to the moving powers of the 

 animal economy, he maintains that digestion, 



