528 PSYCHOLOGY. 



to a similar result. But it is the bane of psychology to 

 suppose that where results are similar, processes must be 

 the same. Psychologists are too apt to reason as geometers 

 would, if the latter were to say that the diameter of a circle 

 is the same thing as its semi-circumference, because, for- 

 sooth, they terminate in the same two points.* 



THE PERCEPTION OP LIKENESS. 



The perception of likeness is practically very much bound 

 up with that of difference. That is to say, tlie only differ- 

 ences we note as differences, and estimate quantitatively, and 

 arrange along a scale, are those comparatively limited dif- 

 ferences which we find between members of a common 

 genus. The force of gravity and the color of this ink are 

 things it never occurred to me to compare until now that I 

 am casting about for examples of the incomparable. 

 Similarly the elastic quality of this india-rubber band, the 

 comfort of last night's sleep, the good that can be done with 

 a legacy, these are things too discrej^ant to have ever been 

 compared ere now. Their relation to each other is less 

 that of difference than of mere logical negativity. To be found 

 different, things must as a rule have some commensurability, 

 some aspect in common, which suggests the possibility of 

 their being treated in the same way. This is of course not 

 a theoretic necessity — for any distinction may be called a 

 * difference,' if one likes — but a practical and linguistic re- 

 mark. 



The same things, then, ivhich arouse the perception of difference 

 usually arouse that of resemblance also. And the analysis of 

 them, so as to define wherein the difference and wherein the 

 resemblance respectively consists, is called comparison. If 

 we start to deal with the things as simply the same or alike, 

 we are liable to be surprised by the difference. If w^e start to 



* Compare Lipps's excellent passage to the same critical effect in his 

 GrundtiUsaclien des Seeleiilebens, pp. 390-R93.— I leave my text just as it 

 was written before the publication of Lange's and Milnsterberg's results 

 cited on pp. 93 and 4-33. Their ■ shortened ' or ' mu.scular ' times, got 

 when the expectant attention wasaddres.sed to the possible reactions rather 

 than to the stimulus, constitule the minimal reaction-time of which Ispeali, 

 and ail thai I say in the text falls beautifully into line with their results. 



