INTRODUCTION. 15 



of the history of the sciences, 1 conceive that I 

 have secured the distribution of my history from 

 material error ; for no merely arbitrary division of 

 the events could satisfy such conditions. But though 

 I have constructed such charts to direct the course 

 of the present history, I shall not insert them in 

 the work, reserving them for the illustration of the 

 philosophy of the subject; for to this they more pro- 

 perly belong, being a part of the Logic of Induction. 



Stationary Periods. By the lines of such maps 

 the real advance of science is depicted, and nothing 

 else. But there are several occurrences of other 

 kinds, too interesting and too instructive to be alto- 

 gether omitted. In order to understand the condi- 

 tions of the progress of knowledge, we must attend, 

 in some measure, to the failures as well as the suc- 

 cesses by which such attempts have been attended. 

 When we reflect during how small a portion of the 

 whole history of human speculations, science has 

 really been, in any marked degree, progressive, we 

 must needs feel some curiosity to know what was 

 doing in these stationary periods ; what field could 

 be found which admitted of so wide a deviation, or 

 at least so protracted a wandering. It is highly 

 necessary to our purpose, to describe the baffled 

 enterprises as well as the achievements of human 

 speculation. 



Deduction. During a great part of such sta- 

 tionary periods, we shall find that the process which 

 we have spoken of as essential to the formation of 



