28 CEREBRAL FORCES. [i. 



as to the former, the mind cannot, by its own power alone, 

 produce the material ideas in the brain, but must wait for 

 the external impressions which form them in the brain ; while, on 

 the other hand, no immediately antecedent impression on the 

 nervous system is necessary to the latter — the ideas of the 

 intellect — but the soul forms them by its own proper power, 

 and lets them follow each other according to their natural 

 psychological laws, free from the restraint of external impressions. 

 Note. — It is necessary to comprehend clearly this difference 

 between the conceptions, otherwise nothing can be accurately 

 distinguished and taught in the physiology of the connection 

 between body and soul ; for this reason, the new expressions 

 must be excused, and their subjoined definitions closely adhered 

 to in the subsequent portions of the work; and there is nothing 

 in them which does not fully harmonise with established psy- 

 chological ideas. 



28. Probably these material ideas and representations of the 

 conceptions in the brain, consist simply in a play of the vital 

 spirits in it ; for when the brain of an animal is examined, there 

 IS nothing visible, of all the animal movements, or at all events 

 of the material ideas ; and its purely mechanical movements in 

 no wise harmonise with the conceptions, but are much more 

 simple, and are in accordance with the mechanism of the cir- 

 culation and respiration. 



29. This fundamental principle of the animal nature of all 

 sentient animals, namely, that every operation of the soul 

 originates, continues, ceases, is defective, and increases or 

 diminishes, in connection with an operation of the animal-sentient 

 force of the brain (25, 26), — connects the souls of animals most 

 intimately with their bodies, and the conceptions with the move- 

 ments, and lays the basis for the whole doctrines of the animal 

 nature of the sentient forces, or in other words, of the union 

 of soul and body, (compare 345). This union is known to, 

 and conceded by, philosophers and physicians, although they 

 explain it in totally different ways ; which explanations, how- 

 ever, are unnecessary and foreign to medical art, because it 

 is of no real importance whether the union be explained 

 '^ materially,'^ ^*^ harmonically," '^influxionistically,'' or ^^occa- 

 sionalistically.'^ And although the peculiar relations of the 

 movements in the brain (its material ideas), which accompany 

 the conceptions be unknown (28), nevertheless their existence 



