D'ALEMBERT. 385 



sure of contemplation, and consequently is an addition 

 to the gratification of exactly the same kind, derived 

 immediately from the contemplation of pure mathe- 

 matical truth; much, indeed, of the mixed mathematics 

 is also purely mathematical investigation, built upon 

 premises derived from induction. The other gratifica- 

 tion is of a wholly different description; it is con- 

 nected merely with the promotion of arts subservient 

 to the ordinary enjoyments of life. This is only a se- 

 condary and mixed use of science to the philosopher ; 

 the main pleasure bestowed by it is the gratification 

 which, by a law of our nature, we derive from con- 

 templating scientific truth, when indulging in the 

 general views which it gives, marking the unexpected 

 relations of things seemingly unconnected, tracing the 

 resemblance, perhaps identity, of things the most un- 

 like, noting the diversity of those apparently similar. 

 This is the true and primary object of scientific inves- 

 tigation. This it is which gives the pleasure of science 

 to the mind. The secular benefits, so to speak, the 

 practical uses derived from it, are wholly independent 

 of this, and are only an incidental, adventitious, secon- 

 dary advantage. I have fully explained this doctrine 

 in the Preliminary Discourse to the works of the So- 

 ciety for the Diffusion of Useful Knowledge, and in 

 the Introduction to the ' Political Philosophy.' It 

 never had been stated, as far as I know, before ; but it 

 rests on such irrefragable principles, that it has not 

 since been called in question.* 



It is an illustration of the happiness derived from 

 mathematical studies, that they possess two qualities in 

 the highest degree, not perhaps unconnected with one 



* It gave me great pleasure to find it highly approved by my revered 

 friend, Professor Stewart, who regarded it as indeed of more value and 

 originality than I had myself considered it. The outline of it had been 

 read many years before (1798) in a literary society at Edinburgh, to which 

 Lord Jeffrey, Dr. Brown, Mr. Homer, and others belonged. See Appen- 

 dix to Life of Robertson, vol. ii. 



2 c 



