10 LECTURE I. 



the boundaries of science in a direction in 

 which we think they admit of extension ? 

 What induces one person to prohibit an- 

 other from theorizing? Is it not because he 

 has himself attempted it in vain, and there- 

 fore deems the attempt unavaihng ? 



Feehngs and opinions are the chief 

 sources of all our intellectual conduct : we 

 ought therefore to cultivate good and ho- 

 nourable feelings, and to scrutinize opinions, 

 with a view to entertain none but those 

 that appear correct ; and such an examin- 

 ation, to which I now invite you, must 

 be allowed to be a proper exercise of in- 

 tellect. 



Since thinking is inevitable, our chief 

 enquiry should be how we ought to think 

 or theorize; and on this point Newton 

 himself has condescended to instruct us. 

 Our theories, hypotheses, or opinions, for 

 to me all these words seem to refer to one 

 and the same act of the mind — should be 

 verifiable or probable, and should rationally 

 account for all the known phaenomena of 



