390 OPERATIONS SUBSIDIARY TO INDUCTION. 



to Induction, it is most true that Induction could not go on without 

 general conceptions. 



§ 2. But it does not therefore follow that these general conceptions 

 must have existed in the mind previously to the comparison. It is not 

 (as Mr. Whewell seems to suppose,) a law of our intellect, that in 

 comparing things with each other and taking note of their agreement 

 we merely recognize as realized in the outward world something that 

 we already had in our minds. The conception originally found its 

 way to us as the result of such a comparison. It was obtained (in 

 metaphysi.^al phrase,) by abstraction from individual things. These 

 things may be things which we perceived or thought of on former 

 occasions, but they may also be the things which we are perceiving or 

 thinking of on the very occasion. When Kepler compared the observed 

 places of the planet Mars, and found that they agreed in being points 

 of an elliptic circumference, he applied a general conception which 

 was already in his mind, having been derived from his former experi- 

 ence. But this is by no means the universal case. When we compare 

 several objects and find them to agree in being white, or when we 

 compare the various species of ruminating animals and find them agree 

 in^being cloven-footed, we have just as much a general conception in our 

 minds as Kepler had in his : we have the conception of " awhite thing," 

 or the conception of " a cloven-footed, animal." But no one supposes 

 that we necessarily bring these conceptions with us, and superinduce 

 them (to adopt Mr. Whewell's expression*) upon the facts : because in 

 these simple cases everybody sees that the very act of comparison which 

 ends in our connecting the facts by means of the conception, may be the 

 source from which we derive the conception itself. If we had never 

 seen any white object or had never seen any cloven-footed animal before, 

 we should at the same time and by the same mental act acquire the idea, 

 and employ it for the colligation of the observed phenomena. Kepler, 

 on the contrary, really had to bring the idea with him, and superinduce 

 it upon the facts ; he could not evolve it out of them : if he had not 

 already had the idea, he would not have been able to acquire it by a 

 comparison of the planet's positions. But this inability was a mere 

 accident : the idea of an ellipse could have been acquired from the 

 paths of the planets as effectually as from anything else, if the paths 

 had not happened to be invisible. If the planet had left a visible 

 track, and we had been so placed that we could see it at the proper 

 angle, we might have abstracted our original idea of an ellipse from 

 the planetary orbit. Indeed, every conception which can be made the 

 instrument for connecting a set of facts, might have been originally 

 evolved from those very facts. The conception is a conception of 

 something ; and that which it is a conception of, is really in the facts, 

 and might, under some supposable circumstances, or by some suppo- 

 sable extension of the faculties which we actually possess, have been 

 detected in them. And not only is this always in itself possible, but 

 it actually happens, in almost all cases in which the obtaining of the 

 right conception is a matter of any considerable difficulty. For if there 

 be no new conception required ; if one of those ali-eady familiar to 

 mankind will serve the purpose, the accident of being the first to 



* Philosophy of the Inductive Sciences, i., 42. 



