ABSTRACTION. 215 



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 some- 

 thing; and that which it is a conception of, is really 

 in the facts, and might, under some supposable cir- 

 cumstances, or by some supposable extension of the 

 faculties which we actually possess, have been detected 

 in them. And not only is this always in itself pos- 

 sible, 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 already 

 familiar to mankind will serve the purpose, the 

 accident of being the first to whom the right one 

 occurs, may happen to almost anybody; at least in 



