14 



ture. The poiat indeed was soon so ob- 

 vious, that, rejecting the two former sets 

 of instructors, I had recourse to Reason 

 and Nature only : — from which sources 

 alone have been collected all I know, 

 with any tolerable degree of certainty up- 

 on the subject. 



However, though neither Books nor 

 Me?i have been serviceable in elucidating, 

 still it is confessed, they have thrown 

 considerable difficulties in the way of dis- 

 cussing the subject. Mens minds are ge- 

 nerally prejudiced in favour of old esta- 

 blished opinions; assertion from one 

 quarter is equal to the same sort of argu- 

 ment from another. — Therefore, before 

 we can w^ork conviction, we must resort 

 to a better species of evidence ; we must, 

 in fact, show the reader, by reasoning 

 from what he already knows, on which 

 side the truth lies. The Book of Nature 

 is open, and we must study it attentive- 

 ly ; otherwise we shall in vain expect the 



