sion of language, that is of an elaborated system of sound-signs, as an absolute cleft between man and the lower animals; a theory which needs for its completion only the other theory that a new absolute cleft has been opened between men who possess the sign-system of writing in letters and those who do not possess it, so that the former cannot be descended from the latter.
18. Now we know that there are different human “languages,” by which we mean the total systems of sound-signs which are understood and used in a certain group of men, in a nation or in related nations. The fact that within such a group smaller groups are again distinguished, chiefly with reference to the sound-forms or “pronunciations” of the same words, but partly also through a certain number of deviating peculiar word-signs, is expressed by saying that within a language we find various “ways of speaking” or “dialects”. As a matter of fact there are in every larger or smaller group of men, who live together and have common experiences, particular words which are regularly used, and are often so considerable and striking that we speak again of a particular “language”—student’s language, sailor’s language, “thieves Latin,” etc. Not seldom, again, there is in the narrowest and smallest groups, as between married people or brothers and sisters, a private language, i.e., numerous names of things which they alone understand or use, and which they, or one of them, have invented; such a name may be an arbitrary and otherwise meaningless sound, or a sound which in other connexions means something else, or a sound attached to one which is thus familiar.
19. It is true that for mutual understanding a common idea-system is as necessary as a common sign-system; nay, more so, for if the ideas are there the signs are more easily and quickly gained, and therefore also substituted; while the knowledge of signs is worthless without knowledge of the ideas to which they are to be referred, and this knowledge is much more difficult to gain or replace, especially when we are no longer dealing with perceivable, but only with thinkable objects. Hence the fact that two men speak the same language is no guarantee for their understanding each other to any great extent. The question here is not only of capacity for perceptions (we speak in vain of colour to the blind), ideas and abstractions, but also of the whole range of specific technical and scientific “concepts,” the names of which help us nothing unless we are familiar with the objects. Finally, for an intimate understanding we need,
