48 HISTORY OF INDUCTIVE SCIENCES. 



tory 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 properly 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 

 altogether omitted. In order to understand the conditions of the 

 progress of knowledge, we must attend, in some measure, to the failures 

 as well as the successes 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 enter- 

 prises as well as the achievements of human speculation. 



Deduction. — During a great part of such stationary periods, we 

 shall find that the process which we have spoken of as essential to 

 the formation of real science, the conjunction of clear Ideas with dis- 

 tinct Facts, was interrupted ; and, in such cases, men dealt with ideas 

 alone. They employed themselves in reasoning from principles, and 

 they arranged, and classified, and analyzed their ideas, so as to make 

 their reasonings satisfy the requisitions of our rational faculties. This 

 process of drawing conclusions from our principles, by rigorous and 

 unimpeachable trains of demonstration, is termed Deduction. In its 

 due place, it is a highly important part of every science ; but it has 

 no value when the fundamental principles, on which the whole of the 

 demonstration rests, have not first been obtained by the induction of 

 facts, so as to supply the materials of substantial truth. Without 

 such materials, a series of demonstrations resembles physical science 

 only as a shadow resembles a real object. To give a real significance 

 to our propositions, Induction must provide what Deduction cannot 

 supply. From a pictured hook we can hang only a pictured chain. 



Distinction of common Notions and Scientific Ideas. 6 — When the 



« Scientific Ideas depend upon certain Fundamental Ideas, which are enumerated 

 in the PhUosophy, book i. ch. 8. 



