JOSEPH PKIESTLEY. 113 



of his life and done more for the advancement of knowl- 

 edge, if he had confined himself to his scientific pursuits 

 and let his fellow-men go their way was true. But it 

 seems to have been Priestley's feeling that he was a man 

 and a citizen before he was a philosopher, and that the 

 duties of the two former positions are at least as impera- 

 tive as those of the latter. Moreover, there are men (and 

 I think Priestley was one of them) to whom the satisfac- 

 tion of throwing down, a triumphant fallacy is as great as 

 that which attends the discovery of a new truth; who 

 feel better satisfied with the government of the world, 

 when they have been helping Providence by knocking 

 an imposture on the head ; and who care even more for 

 freedom of thought than for mere advance of knowl- 

 edge. These men are the Carnots who organise victory 

 for truth, and they are, at least, as important as the gen- 

 erals who visibly fight her battles in the field. 



Priestley's reputation as a man of science rests upon 

 his numerous and important contributions to the chem- 

 istry of gaseous bodies ; and to form a just estimate of 

 the value of his work of the extent to which it ad- 

 vanced the knowledge of fact and the development of 

 sound theoretical views we must reflect what chemis- 

 try was in the first half of the eighteenth century. 



The vast science which now passes under that name 

 had no existence. Air, water, and fire were still counted 

 among the elemental bodies; and though Yan Hel- 

 mont, a century before, had distinguished different kinds 



