PREFACE. v 



di lions necessary to the multiform manifesta- 



j tni 



lions of the mind. 

 '" 

 1'eoplc liaving the idea that every thing is 



valuable for some secondary object ; this object 

 to which an imaginary value is attached varies 

 in the minds of different persons, according to 

 their own particular conformation of mind and 

 to their education. In many, the aggrandize- 

 ment of property being the prevailing passion, 

 scarcely any thing is considered useful, except 

 that which contributes to public or private 

 wealth. In others, the degree in which any 

 science or art can contribute to common conve- 

 nience, or abridge labour, becomes the measure 

 of their estimation of it. Judging of others 

 by themselves, people have supposed that the 

 sciences have always been cultivated for such 

 secondary reasons, and that in the early stages 

 of society, they arose out of the numerous arti- 

 ficial wants which advancing civilization was 

 continually producing. But though it has ge- 

 nerally been the case with the multitude who 

 have followed up the discoveries of the inge- 

 nious, that availing themselves of the intellect 

 of their superiors, they have erected a trade on 

 their inventions, or have converted them to 

 purposes of social improvement ; yet many of 



