158 INDUCTION. 



blances and dissimilarities, and is the sum total 01 

 what Logic has to teach on the subject. 



An undue extension of these views induced Locke 

 to consider reasoning itself as nothing hut the com- 

 parison of two ideas through the medium of a third, 

 and knowledge as the perception of the agreement or 

 disagreement of two ideas: doctrines which the Con- 

 dillac school blindly adopted, without the qualifica- 

 tions and distinctions with which they were studiously 

 guarded by their illustrious author. Where, indeed, 

 the agreement or disagreement (otherwise called re- 

 semblance or dissimilarity) of any two things is the 

 very matter to be determined, as is the case parti- 

 cularly in the sciences of quantity and extension, 

 there the process by which a solution, if not attainable 

 by direct perception, must be indirectly sought, con- 

 sists in comparing these two things through the 

 medium of a third. But this is far from being true 

 of all inquiries. The knowledge that bodies fall to 

 the ground is not a perception of agreement or dis- 

 agreement, but of a series of physical occurrences, a 

 succession of sensations. Locke's definitions of know- 

 ledge and of reasoning required to be limited to our 

 knowledge of, and reasoning about, Resemblances. 

 Nor, even when thus restricted, are the propositions 

 strictly correct; since the comparison is not made, as 

 he represents, between the ideas of the two pheno- 

 mena, but between the phenomena themselves. This 

 mistake has been pointed out in an earlier part of our 

 inquiry*, and we traced it to an imperfect conception 

 of what takes place in mathematics, where very often 

 the comparison is really made between the ideas, 

 without any appeal to the outward senses; only, 



Supra, vol. i., p. 117, 309. 



