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 and the import of Propositions) which had been suggested and in part worked out in the morning conversations already spoken of. Having secured these thoughts from being lost, I pushed on into the other parts of the subject, to try whether I could do anything further towards clearing up the theory of logic generally. I grappled at once with the problem of Induction, postponing that of Reasoning, on the ground that it is necessary to obtain premises before we can reason from them. Now, Induction is mainly a process for finding the causes of effects: and in attempting to fathom the mode of tracing causes and effects in physical science, I soon saw that in the more perfect of the sciences, we ascend, by generalization from particulars, to the tendencies of causes considered singly, and then reason downward from those separate tendencies, to the effect of the same causes when combined. I then asked myself, what is the ultimate analysis of this deductive process; the common theory of the syllogism evidently throwing no light upon it. My practice (learnt from Hobbes and my father) being to study abstract principles by means of the best concrete instances I could find, the Composition of Forces, in dynamics, occurred to me as the most complete example of the logical process I was investigating. On examining, accordingly, what the mind does when it applies the principle of the Composition of Forces, I found that it