INTRODUCTION. 43 



nere to treat, are those which are commonly known as the Physical 

 Sciences; and that by Induction is to be understood that process of 

 collecting general truths from the examination of particular facts, by 

 which such sciences have been formed. 



There are, however, two or three remarks, of which the application 

 will occur so frequently, and will tend so much to give us a clearer 

 view of some of the subjects which occur in our history, that I will 

 state them now in a brief and general manner. 



Facts and Ideas} — In the first place then, I remark, that, to the 

 formation of science, two things are requisite ; — Facts and Ideas ; 

 observation of Things without, and an inward effort of Thought ; or, 

 in other words, Sense and Reason. Neither of these elements, by 

 itself, can constitute substantial general knowledge. The impressions 

 of sense, unconnected by some rational and speculative principle, can 

 only end in a practical acquaintance with individual objects; the op- 

 erations of the rational faculties, on the other hand, if allowed to go on 

 without a constant reference to external things, can lead only to empty 

 abstraction and barren ingenuity. Real speculative knowledge de- 

 mands the combination of the two ingredients ; — right reason, and 

 facts to reason upon. It has been well said, that true knowledge is the 

 interpretation of nature ; and therefore it requires both the interpreting 

 mind, and nature for its subject ; both the document, and the ingenuity 

 to read it aright. Thus invention, acuteness, and connection of thought, 

 are necessary on the one hand, for the progress of philosophical knowl- 

 edge ; and on the other hand, the precise and steady application of 

 these faculties to facts well known and clearly conceived. It is easy 

 to point out instances in which science has failed to advance, in con- 

 sequence of the absence of one or other of these requisites ; indeed, 

 by far the greater part of the course of the world, the history of most 

 times and most countries, exhibits a condition thus stationary with 

 respect to knowledge. The facts, the impressions on the senses, on 

 which the first successful attempts at physical knowledge proceeded, 

 were as well known long before the time when they were thus turned 

 to account, as at that period. The motions of the stars, and the 

 effects of weight, were familiar to man before the rise of the Greek 

 Astronomy and Mechanics : but the " diviner mind" was still absent ; 

 the act of thought had not been exerted, by which these facts were 

 bound together under the form of laws and principles. And even at 



2 For the Antithesis of Fads and Ideas, see the Philosophy, book i. ch. 1, 2, 4, 5. 



