ABSTRACTION. 



427 



tent branches of knowledge, it was 

 shown that the facts of each of them 

 did present, in some instances at 

 least, the curious phenomenon of 

 opposite properties in opposite direc- 

 tions? The thing was superficially 

 manifest only in two cases, those of 

 the magnet and of electrified bodies ; 

 and there the conception was encum- 

 bered with the circumstance of mate- 

 rial poles, or fixed points in the body 

 itself, in which points this opposition 

 of properties seemed to be inherent. 

 The first comparison and abstraction 

 had led only to this conception of 

 poles ; and if anything corresponding 

 to that conception had existed in the 

 phenomena of chemistry or optics, the 

 difficulty now justly considered so 

 great would have been extremely 

 small. The obscurity arose from the 

 fact that the polarities in chemistry 

 and optics were distinct species, 

 though of the same genus, with the 

 polarities in electricity and magne- 

 tism ; and that in order to assimilate 

 the phenomena to one another it was 

 necessary to compare a polarity with- 

 out poles, such, for instance, as is 

 exemplified in the polarisation of 

 light, and the polarity with (apparent) 

 poles, which we see in the magnet ; 

 and to recognise that these polarities, 

 while different in many other respects, 

 agree in the one character which is 

 expressed by the phrase, opposite pro- 

 perties in opposite directions. From 

 the result of such a comparison it 

 was that the minds of scientific men 

 formed this new general conception, 

 between which, and the first confused 

 feeling of an analogy between some 

 of the phenomena of light and those 

 of electricity and magnetism there is 

 a long interval, filled up by the labours 

 and more or less sagacious suggestions 

 of many superior minds. 



The conceptions, then, which we 

 employ for the colligation and methodi- 

 sation of facts, do not develop them- 

 selves from within, but are impressed 

 upon the mind from without ; they 

 are never obtained otherwise than by 

 way of comparison and abstraction. 



and, in the most important and the 

 most numerous cases, are evolved by 

 abstraction from the very phenomena 

 which it is their oflfice to colligate. 

 I am far, however, from wishing to 

 imply that it is not often a very diffi- 

 cult thing to perform this process of 

 abstraction well, or that the success 

 of an inductive operation does not, in 

 many cases, principally depend on the 

 skill with which we perform it. Bacon 

 was quite justified in designating a.s 

 one of the principal obstacles to good 

 induction, general conceptions wrongly 

 formed, "notiones temer^ k rebus 

 abstractae ; " to which Dr. Whewell 

 adds, that not only does bad abstrac- 

 tion make bad induction, but that 

 in order to perform induction well, 

 we must have abstracted well ; our 

 general conceptions must be "clear" 

 and "appropriate" to the matter in 

 hand. 



§ 3. In attempting to .show what 

 the difficulty in this matter really is, 

 and how it is surmounted, I must 

 beg the reader, once for all, to bear 

 this in mind ; that although, in dis- 

 cussing the opinions of a different 

 school of philosophy, I am willing to 

 adopt their language, and to speak, 

 therefore, of connecting facts through 

 the instrumentality of a conception, 

 this technical phraseology means 

 neit"her more nor less than what is 

 commonly called comparing the facts 

 with one another and determining in 

 what they agree. Nor has the techni- 

 cal expression even the advantage of 

 being metaphysically correct. The 

 facts are not connected, except in a 

 merely metaphorical acceptation of 

 the term. The ideas of the facts may 

 become connected, that is, we may 

 be lead to think of them together ; 

 but this consequence is no more than 

 what may be produced by any casual 

 association. What really takes place 

 is, I conceive, more philosophically 

 expressed by the common word Com- 

 parison, than by the phrases "to con- 

 nect" or "to superinduce." For as the 

 general conception is itself obtained 



