CH. II.] EXTERNAL SENSATIONS. 33 



in so far as they are at the same time sensitive nerves. In the 

 Third Chapter we shall state how far the animal forces of both 

 kinds of impressions on the nerves act on the mechanical 

 machines appropriated to the motion of animal bodies^ and in 

 particular how far they regulate these, as animal-sentient forces 

 of the nerves (8). But how do the impressions, per se, act on 

 the nervous system ? And what animal forces, and especially 

 what animal-sentient forces, become thereby participants in that 

 action ? 



On External Sensations. 



34. When a nerve of a sentient animal receives an external 

 impression, it is transmitted along it, and unanimous observa- 

 tions show, that at each impression, certain animal actions 

 result therefrom, either in the brain, from which the nerve 

 arises (12), or in those parts of the body with which it is in 

 connection ; but these actions no longer result, even when the 

 external impression is made, if its transmission to the structure 

 in which they previously took place be prevented by section 

 or ligature of the nerve (43). This transmission takes place 

 from the point of impression upwards (31, 32), and either 

 arrives at the brain or not. Both cases occur in nature (see 

 illustrations of the latter in 47-51). In* the former case, the 

 external impression entering the brain, instantaneously develops 

 that material idea in it which is required for the development 

 of the conception it originates. Since the conceptions [Vorstel- 

 lungen] thus excited in the mind by external impressions are 

 termed ea^ternal sensations, this animal force of the nerves, 

 in virtue of which they excite sensations by means of external 

 impressions, is termed their sensational force, or sensibility 

 [Empfindlichkeit], — (see § 62). 



Note. — The word sensation [Empfindung] is commonly used 

 in a threefold sense. 1. As in the preceding sentence, where 

 it expresses the involuntary sensations [Vorstellungen], which 

 we obtain through the nerves of the external senses. 2. When 

 it expresses the inner feeling of the soul, — its consciousness 

 of itself (80). 3. When it denotes generally the perception 

 [Vorstellung] of the existing condition indefinitely, or equally, 

 whether this perception be excited by an external impression or 

 not. It is of the highest importance, that these three meanings 



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