CH. II.] CEREBRAL IMPRESSIONS. 73 



action ought to be developed ; as, for example, when the spinal 

 cord, or the trunk or branch of a nerve, is tied, compressed, or 

 divided below the point, or mechanical machine, to which the 

 sensation ought to be transmitted (128, 129, iii). 



iv. When the sentient action produced by a nerve consists 

 in a movement of a mechanical machine, to which the nerve is 

 distributed, its production is prevented when the machine is 

 not in a condition to effect the movement organically ap- 

 propriate to it (129, iv). 



135. When sentient actions produced by means of the nerves, 

 are caused by spontaneous conceptions, they may be prevented 

 as follows : — 



i. When the material idea of the conception at the origin of 

 the nerve appropriate to the sentient action cannot so make 

 its impression, that it may be transmitted (130, i). 



ii. When the further transmission cannot take place (134, 

 iii, iv). 



136. There are various kinds of conceptions which do not 

 usually develope sentient actions in the body through the nerves, 

 as inferences, witty thoughts, &c. — (vide 238, 249, 330); nay, 

 many external sensations and other conceptions which ordinarily 

 develope sentient actions through the nerves do not do it, 

 although the animal is in its natural condition. Consequently, 

 just as there are material hinderances which prevent the 

 continuous transmission of many external impressions to the 

 brain (47 — 51), so similar hinderances may prevent the sentient 

 actions of conceptions, and it is a matter of importance to 

 know every possible hinderance of this kind. 



i. Nature has so distributed the origins of the nerves in the 

 brain, that every material idea of a conception has not neces- 

 sarily relations with any of them, or if it excite one origin, it 

 does not necessarily excite all the others at the same time, 

 or even any one origin. Consequently, when material ideas 

 are formed at points of the brain from whence no nerves arise, 

 they excite no sentient action through the nerves (124). Nay, 

 when the material ideas of external sensations, or other concep- 

 tions duly (sinnlich) impress the origin of a nerve, and excite 

 sentient actions through it, all other origins of nerves may 

 remain unaffected thereby, and no sentient actions result, 

 unless under special circumstances (124). 



