PREFACE. 



IT may be truly asserted that the rapid progress of 

 the physical sciences during the last three centuries has 

 not been accompanied by a corresponding advance in 

 the theory of reasoning. Physicists speak familiarly of 

 Scientific Method, but they could not readily describe 

 what they mean by that expression. Profoundly engaged 

 in the study of particular classes of natural phenomena, 

 they are usually too much engrossed in the immense and 

 ever-accumulating details of their special sciences, to 

 generalize upon the methods of reasoning which they 

 unconsciously employ. Yet few will deny that these 

 methods of reasoning ought to be studied, especially by 

 those who endeavour to introduce scientific order into less 

 successful and methodical branches of knowledge. 



The application of Scientific Method cannot be re- 

 stricted to the sphere of lifeless objects. We must sooner 

 or later have strict sciences of those mental and social 

 phenomena, which, if comparison be possible, are of 

 more interest to us than purely material phenomena. 

 But it is the proper course of reasoning to proceed from 

 the known to the unknown from the evident to the 

 obscure from the material and palpable to the subtle 

 and refined. The physical sciences may therefore be 

 properly made the practice-ground of the reasoning 



