I JOSEPH PRIESTLEY 27 



and Michell, and had been led to admit the suffi- 

 ciently obvious truth that our knowledge of matter 

 is a knowledge of its properties ; and that of its 

 substance if it have a substance we know no- 

 thing. And this led to the further admission that, 

 so far as we can know, there may be no difference 

 between the substance of matter and the substance 

 of spirit (" Disquisitions," p. 16). A step farther 

 would have shown Priestley that his materialism 

 was, essentially, very little different from the 

 Idealism of his contemporary, the Bishop of Cloyne. 



As Priestley's philosophy is mainly a clear state- 

 ment of the views of the deeper thinkers of his day, 

 so are his political conceptions based upon those of 

 Locke. Locke's aphorism that " the end of govern- 

 ment is the good of mankind," is thus expanded by 

 Priestley : 



" It must necessarily be understood, therefore, whether it be 

 expressed or not, that all people live in society for their mutual 

 advantage ; so that the good and happiness of the members, 

 that is, of the majority of the members, of any state, is the 

 great standard by which everything relating to that state must 

 finally be determined." l 



The little sentence here interpolated, " that is, 

 of the majority of the members of any state," ap- 

 pears to be that passage which suggested to 

 Bentham, according to his own acknowledgment, 

 the famous " greatest happiness " formula, which 



1 Essay on the First Principles of Government. Second 

 edition, 1771, p. 13. 



