8 PREFACE. 



have as yet seen nothing to disturb, that 1 should be able to 

 speak impartially of the great scientific men of all ages, even 

 of our own. 



I have already said, in the Introduction, that the work 

 aimed at being, not merely a narration of the facts in the 

 history of Science, but a basis for the Philosophy of Science. 

 It seemed to me that our study of the modes of discovering 

 truth ought to be based upon a survey of the truths which 

 have been discovered. This maxim, so stated, seems suffi- 

 ciently self-evident ; yet it has, even up to the present time, 

 been very rarely acted on. Those who discourse concerning 

 the nature of Truth and the mode of its discovery, still, com- 

 monly, make for themselves examples of truths, which for 

 the most part are utterly frivolous and unsubstantial (as in 

 most Treatises on Logic) ; or else they dig up, over and over, 

 the narrow and special field of mathematical truth, which 

 certainly cannot, of itself, exemplify the general mode by 

 which man has attained to the vast body of certain truth 

 which he now possesses. 



Yet it must not be denied that the Ideas which form the 

 basis of Mathematical Truth are concerned in the formation 

 of Scientific Truth in general ; and discussions concerning 

 these Ideas are by no means necessarily barren of advantage. 

 But it must be borne in mind that, besides these Ideas, there 

 are also others, which no less lie at the root of Scientific 

 Truth ; and concerning which there have been, at various 

 periods, discussions which have had an important bearing on 

 the progress of Scientific Truth ; such as discussions con- 

 cerning the nature and necessary attributes of Matter, of 

 Force, of Atoms, of Mediums, of Kinds, of Organization. 

 The controversies which have taken place concerning these 

 haye an important place in the history of Natural Science in 



