378 ZOOLOGICAL PHILOSOPHY 



attach conventional signs to the conceptions we acquire, in order that 

 these conceptions may not remain isolated, but may be associated and 

 compared, and their relationships determined. But these signs are 

 artificial aids, infinitely useful in helping us to think, and not immediate 

 causes of formation of ideas. 



Signs of whatever kind do no more than assist our recollection of 

 conceptions acquired recently or long ago, furnish us means of bringing 

 them back into consciousness, and thereby facilitate the formation of 

 new ideas. 



Condillac has successfully proved that without signs man could never 

 have extended his ideas as he has done and still does ; but it does 

 not follow that signs are themselves elements in ideas. 



I greatly regret that I cannot continue the important discussion 

 which this subject demands ; but probably some one will see the 

 mistake to which I have drawn attention, and furnish a complete proof 

 of it. Then while recognising all that we owe to the art of signs, we 

 shall recognise at the same time that it is only an art and consequently 

 outside nature. 



From the observations and considerations set forth in this chapter 

 I conclude : 



L That the various acts of the understanding require a special organ 

 or system of organs, just as one is required for feehng, another for move- 

 ment, and a third for respiration, etc. ; 



2. That in the performance of acts of intelligence the movement of 

 the nervous fluid is the only active factor, while the organ remains 

 passive though contributing to the diversity of the operations by a 

 corresponding diversity of its parts and of the impressions preserved 

 upon them ; — a diversity that cannot be calculated since it increases 

 up to infinity according as the organ is used ; 



3. That acquired ideas are the material of aU operations of the under- 

 standing ; that with this material the individual who habitually exerts 

 his intellect may be continually forming new ideas, and that the only 

 means open to him for this extension of his ideas consists in the art of 

 signs to assist his memory, an art which man alone can use, which he 

 makes more perfect every day, and without which his ideas would 

 inevitably remain very Umited. 



To throw further hght on the subject imder discussion, I shall now 

 pass to an examination of the principal acts of the understanding, 

 that is to say, those of the first order from which all the rest are 

 derived. 



