children that have been carefully observed, sentences come much later than single words.
Children, at first, are limited as to their power of producing sounds, and also by the paucity of their learned associations. I am sure the reason why "ma-ma" and "da-da" have the meaning they have is that they are sounds which infants make spontaneously at an early age, and are therefore convenient as sounds to which the elders can attach meaning. In the very beginning of speech there is not imitation of grown-ups, but the discovery that sounds made spontaneously have agreeable results. Imitation comes later, after the child has discovered that sounds can have this quality of "meaning". The type of skill involved is throughout exactly similar to that involved in learning to play a game or ride a bicycle.
We may sum up this theory of meaning in a simple formula. When through the law of conditioned reflexes, A has come to be a cause of C, we will call A an "associative" cause of C, and C an "associative" effect of A. We shall say that, to a given person, the word A, when he hears it, means" C, if the associative effects of A are closely similar to those of C; and we shall say that the word A, when he utters it, "means" C, if the utterance of A is an associative effect of C, or of something previously associated with C. To put the matter more concretely, the word "Peter" means a certain person if the associative effects of hearing the word "Peter" are closely similar to those of seeing Peter, and the associative causes of uttering the word "Peter" are occurrences previously associated with Peter. Of course as our experience increases in complexity this simple schema becomes obscured and overlaid, but I think it remains fundamentally true.
There is an interesting and valuable book by Messrs. C. K. Ogden and I. A. Richards, called The Meaning of Meaning. This book, owing to the fact that it concentrates on the causes of uttering words, not on the effects of hearing them, gives only half the above theory, and that in a somewhat incomplete form. It says that a word and its meaning
