THEORY OF KNOWLEDGE. lOl those which have disappeared, or, as it were, have been put aside. For an idea to be "in the memory" means that the mind has the capacity to reproduce it at will, whereupon it recognizes it as previously experienced. If our ideas are not freshened up from time to time by nc w impressions of the same sort they gradually fade out, until finally (as the idea of color in one become blind in early life) they com- pletely disappear. Ideas impressed upon the mind by frequent repetition are rarely entirely lost. Memory is the basis for the intellectual functions of discernment and com- parison, of composition, abstraction, and naming. Since, amid the innumerable multitude of ideas, it is not possible to assign to each one a definite sign, the indispensable con- dition of language is found in the power of abstraction, that is, in the power of generalizing ideas, of compounding many ideas into one, and of indicating by the names of the gen- eral ideas, or of the classes and species, the particular ideas also which are contained under these. Here is the great distinction between man and the brute. The brute lacks language because he lacks (not all understanding whatever, e.g., not a capacity, though an imperfect one, of compari- son and composition, but) the faculty of abstraction and of forming general ideas. The object of language is simply the quick and easy communication of our thoughts to others, not to give expression to the real essence of objects Words are not names for particular things, but signs of general ideas ; and abstracta nothing more than an artifice for facilitating intellectual intercourse. This abbreviation, which aids in the exchange of ideas, involves the danger that the creations of the rrind denoted by words will be taken for images of real general essences, of which, in fact, there are none in existence, but only particular things. In order to prevent anyone to whom I am speaking from understand- ing my words in a different sense from the one intended, it is necessary for me to define the complex ideas by analyzing them into their elements, and, on the other hand, to give examples in experience of the simple ideas, which do not admit of definition, or to explain them by synonyms. Thus much from Locke's philosophy of language, to which he devotes the third book of the Essay.
