And here it becomes manifest that not only is classification carried on by grouping together in the mind things that are like; but that classes and sub-classes are formed and arranged according to the degrees of unlikeness.  Things widely contrasted are alone distinguished in the lower stages of mental evolution; as may be any day observed in an infant.  And gradually as the powers of discrimination increase, the widely contrasted classes at first distinguished, come to be each divided into sub-classes, differing from each other less than the classes differ; and these sub-classes are again divided after the same manner.  By the continuance of which process, things are gradually arranged into groups, the members of which are less and less unlike; ending, finally, in groups whose members differ only as individuals, and not specifically.  And thus there tends ultimately to arise the notion of complete likeness.  For, manifestly, it is impossible that groups should continue to be subdivided in virtue of smaller and smaller differences, without there being a simultaneous approximation to the notion of no difference.

Let us next notice that the recognition of likeness and unlikeness, which underlies classification, and out of which continued classification evolves the idea of complete likeness—­let us next notice that it also underlies the process of naming, and by consequence language.  For all language consists, at the beginning, of symbols which are as like to the things symbolised as it is practicable to make them.  The language of signs is a means of conveying ideas by mimicking the actions or peculiarities of the things referred to.  Verbal language is also, at the beginning, a mode of suggesting objects or acts by imitating the sounds which the objects make, or with which the acts are accompanied.  Originally these two languages were used simultaneously.  It needs but to watch the gesticulations with which the savage accompanies his speech—­to see a Bushman or a Kaffir dramatising before an audience his mode of catching game—­or to note the extreme paucity of words in all primitive vocabularies; to infer that at first, attitudes, gestures, and sounds, were all combined to produce as good a likeness as possible, of the things, animals, persons, or events described; and that as the sounds came to be understood by themselves the gestures fell into disuse:  leaving traces, however, in the manners of the more excitable civilised races.  But be this as it may, it suffices simply to observe, how many of the words current among barbarous peoples are like the sounds appertaining to the things signified; how many of our own oldest and simplest words have the same peculiarity; how children tend to invent imitative words; and how the sign-language spontaneously formed by deaf mutes is invariably based upon imitative actions—­to at once see that the nation of likeness is that from which the nomenclature of objects takes its rise.