151 



OF THE INTELLIGENCE AND OF INSTINCT. 



306. Having examined the organs by which man and 

 other animals acquire their knowledge, there remains the 

 study of the power which determines their actions and the 

 phenomena of the understanding. This branch of physiology 

 having been more cultivated by philosophers than naturalists, 

 we shall confine our remarks thereon to a brief space. 



It is man alone who possesses the faculties we allude to in 

 a high order, and it is man who naturally has been most 

 observed in this respect; our comparisons have reference 

 constantly to man ; by him we judge of other animals. 



307. Faculties of the Human Understanding. Im- 

 pressions made on the external senses by the external world 

 are transmitted to the brain by the nerves : they are then 

 called sensations. Sensation, then, is quite distinct from an 

 impression ; it is an impression perceived ; it implies con- 

 sciousness ; what is not perceived has no existence for us. 

 The perceiving faculty is usually spoken of as the mind, the 

 spirit (esprit), the soul ; the thinking, perceiving, and reflect- 

 ing power, conscious of its own independent existence. 



308. Over this consciousness we have no power during 

 sleep, but when awake we can direct it to one object to the 

 exclusion of others. When thus forcibly and strongly called 

 on by one impression, pain ceases to be felt, and the external 

 world is no longer observed. This faculty is called the power 

 of attention, which varies almost in every individual. 



309. The constant relation of certain sensations to cer- 

 tain impressions leads to the inference that the one causes 

 the other ; that the one is the effect, the other the cause. We 

 arrive at this conclusion by the natural powers of induction. 

 We thus acquire a knowledge of the external world, and we 

 learn to judge by comparison of the different qualities of 

 objects. 



Soon the mind does not stop at this point, but proceeds to 

 weigh more and more carefully the impressions and sensations 

 thus received; the faculty of judging and comparing be- 

 comes rapid and surer; it is not the senses which are 

 exercised, it is the judgment ; the organs of sense require no 

 education. And here man's faculties would stop, were it not 

 for another faculty, by which sensations long since received 

 can be recalled, and compared with each other and with those 

 then and there present. 



