ABSTRACTION*. 199 



they are an indefinite number, a type of some sort is an indis 

 pensable condition of the comparison. When we have to 

 arrange and classify a great number of objects according to 

 their agreements and differences, we do not make a confused 

 attempt to compare all with all. We know that two things 

 are as much as the mind can easily attend to at a time, and 

 we therefore fix upon one of the objects, either at hazard or 

 because it offers in a peculiarly striking manner some important 

 character, and, taking this as our standard, compare it with 

 one object after another. If we find a second object which 

 presents a remarkable agreement with the first, inducing us to 

 class them together, the question instantly arises, in what 

 particular circumstances do they agree ? and to take notice of 

 these circumstances is already a first stage of abstraction, 

 giving rise to a general conception. Having advanced thus 

 far, when we now take in hand a third object we naturally ask 

 ourselves the question, not merely whether this third object 

 agrees with the first, but whether it agrees with it in the same 

 circumstances in which the second did ? in other words, whe 

 ther it agrees with the general conception which has been 

 obtained by abstraction from the first and second ? Thus we 

 see the tendency of general conceptions, as soon as formed, to 

 substitute themselves as types, for whatever individual objects 

 previously answered that purpose in our comparisons. We 

 may, perhaps, find that no considerable number of other objects 

 agree with this first general conception ; and that we must 

 drop the conception, and beginning again with a different indi 

 vidual case, proceed by fresh comparisons to a different general 

 conception. Sometimes, again, we find that the same concep 

 tion will serve, by merely leaving out some of its circumstaiices ; 

 and by this higher effort of abstraction, we obtain a still more 

 general conception ; as in the case formerly referred to, the 

 scientific world rose from the conception of poles to the general 

 conception of opposite properties in opposite directions ; or as 

 those South-Sea islanders, whose conception of a quadruped 

 had been abstracted from hogs (the only animals of that de 

 scription which they had seen), when they afterwards compared 

 that conception with other quadrupeds, dropped some of the 



