CH. II.] EXTERNAL SENSATIONS. 45 



of his mill, that he does not hear it at all, or only with an in- 

 distinct consciousness. Again, we know that when the mind 

 is abstracted from other conceptions, and devotes itself to one 

 only (an act termed attention) ^ it can only do this by a cessa- 

 tion of the movements in the brain; or, in other words, of 

 the material ideas of the conceptions from which it is ab- 

 stracted (21). Such a repose of the brain probably takes 

 place in cases of the kind under consideration. 



52. When the nerves of an organism receive external im- 

 pressions with greater comparative facility, and when the latter 

 meet with fewer or less important natural obstructions to their 

 transmission to the brain, and to the formation of material 

 external sensations therein (47, 51), the organism is termed 

 sensitive, in a special sense [excitablej susceptible) ; or, if the con* 

 trary, insensible (harsh, unfeeling); and the qualities themselves 

 are termed individual sensibility (94), individual insensibility. 

 The property of animal nature, in relation to sensibility and 

 insensibility, is the temperament of an animal body : the bodily 

 constitution, — the nature. By habit, sensitive organisms become 

 insensible ; consequently the temperament is changed, and this 

 may take place in all the modes indicated (51). An individual 

 sensibility towards certain external impressions, not shown by 

 the majority of persons of a similar temperament, is termed 



53. Mental philosophers maintain, that external sensations 

 have greater strength than other conceptions, because they 

 consist of a greater number of elements [merkmalen], 

 (Baumgarten's ' Metaphysics,' § 402). Now, since each element 

 of a conception is also a conception itself, and every conception 

 requires a material idea in the brain (25), it follows, that the 

 material ideas of external sensations are compounded of more 

 movements in the brain, than the material ideas of all other 

 conceptions. Consequently, they exceed the latter in intensity, 

 that is to say, the movements in the brain which external 

 sensations produce, are greater, and consequently have greater 

 results, than those which accompany other conceptions. 



54. Every thing that enfeebles external sensations, diminishes 

 also the force of their material ideas in the brain, and of their 

 action in the organism ; and this diminution of force can take 

 place by the same means, that enfeeble the external sensations 



