276 The Older Doctrines [lect. 



" nervous system. These, being distributed by the brain, as from 

 " a fount, along the nerves over the whole body, imbue, irradiate, 

 "and fill all parts, inducing in each a certain tenseness. So 

 "that the ducts of the nervous structures, like cords lightly 

 " strung, are extended from the brain and its appendages in 

 " every direction to all peripheral parts. And these are so strung 

 " and so actuated by a certain continuity of the soul (the corporeal 

 " soul), that if either extremity be struck, the blow is forthwith 

 " felt throughout the whole. Hence any intention conceived 

 '* within the brain immediately carries out the purposed work 

 " in the proper member or part, and vice versa, any impulse or 

 * blow which is inflicted from without on any member or sensitive 

 '• organ is immediately communicated to the brain. When the 

 " impression or impetus passes outwards from the brain along 

 " the nerves to motor structures, movement is produced. If on 

 " the other hand the impression started from without is carried 

 "inwards towards the brain, sensation is the result. While 

 " either of these is taking place, we must not suppose (as is 

 " commonly stated) that the same spirits rush at once from one 

 "goal to another as in a race-course or circus, and then rush 

 "back again; but since the soul by reason of a certain con- 

 " tinuity is expanded over the whole, and its particles, that is 

 " to say the spirits, are arranged touching each other, drawn up 

 " as it were in line, so these, in military fashion, perform their 

 " functions, keeping their ranks without leaving their stations, 

 " and whether arranged in active fighting order, or passively as 

 " a mirror, themselves immobile, on the one hand obey the 

 " commands of the brain sent down from without, and so bring 

 "about movements, or on the other hand, pass straight on to 

 " the brain the message impressed on them by the sensitive 

 " structures, and thus give rise to sensation. So the same 

 " animal spirits bring about both movement and sensation, by 

 " their own opposite and inverse disposition and aspect." 



And he explains diversity of functions by the argument, 

 "that it does not seem contrary to reason to suppose that 

 " within the basis of the sensitive soul and indeed within the 

 " same part of it, certain spirituous particles may be in move- 

 " ment while others remain at rest." 



