392 THE POPULAR SCIENCE MONTHLY. 



these two things. Of such shocks is made up one-half of what we 

 term knowledge. 



Whenever there is a difference it should be felt by us ; and so 

 wherever there is an agreement it should be felt. To overlook either 

 the one or the other is stupidity of mind. Our education marches in 

 both lines ; and, in so far as we are helped by the schoolmaster, we 

 should be helped in both. The artifices that promote discrimination, 

 and the influences that thwart it, have been already considered; and 

 many of the observations apply also to agreement. In the identify- 

 ing of like in the midst of unlike, there are cases that are easy ; and 

 there are cases that the unassisted mind fails to perceive. 



1. We must repeat, with reference to the delicate perception of 

 Agreements, the antithesis of the intellectual and the emotional out- 

 goings. It is in the stillness of the emotions that the higher intel- 

 lectual exercises are possible. This circumstance should operate as a 

 warning against the too frequent recourse to pains and penalties, as 

 well as against pleasurable and other excitement. But a more spe- 

 cific application remains. 



We may at once face the problem of general knowledge. The 

 most troublesome half of the education of the intellect is the getting 

 possession of generalities. A general fact, notion, or truth, is a fact 

 recurring under various circumstances or accompaniments : " heat " 

 is the name for such a generality ; there are many individual facts 

 greatly differing among themselves, but all agreeing in the impression 

 called heat the sun, a fire, a lamp, a living animal. The intellect 

 discerns, or is struck with, the agreement, notwithstanding the differ- 

 ences; and in this discernment arrives at a general idea. 



Now the grand stumbling-block in the way of the generalizing 

 impetus is the presence of the individual differences. These may 

 be small and insignificant ; in comparing fires with one another, the 

 agreement is striking, while the difierences between one fire and an- 

 other, in size, or intensity, or fuel, do not divert the attention from 

 their agreement. But the discerning of sameness in the sun's ray 

 and in a fermenting dung-heap is thwarted by the extraordinary 

 disparity; and this conflict between the sameness and the differ- 

 ence operates widely and retards the discovery of the most important 

 truths. 



2. The device of juxtcqjosition applies to the expounding of 

 agreement, no less than of difTerence. We can arrange the several 

 agreeing facts in such a way that the agreement is more easily seen. 

 The efiect is gained partly by closeness, as in the case of difierences, 

 and partly by a symmetrical contact, as when we compare the two 

 hands by placing them finger to finger, and thumb to thumb. Such 

 symmetrical comparisons bring to view, in the same act, agreement 

 and difierence. The method reaches far and wide, and is one of the 

 most powerful artificial aids to the imparting knowledge. 



