From the INTRODUCTION.
A word represents an idea. The nature of a man's ideas determines the nature of his words. The mind of a man, the mind of a people, is reflected in the language of the man, the language of the people. Good words are begotten by good thoughts; evil words arise from evil thoughts. The source of an idea is at the same time the source of the word to express that idea. Thought and language are inseparable. As a man's character is, such is the nature of his true vocabulary.
An idea is represented by a word; a group or combination of ideas is represented by a group or combination of words. The larger a man's vocabulary, the greater the number of his specific ideas. He who has an immense vocabulary not only has a great number of specific ideas, but also has the possibilities of an enormous number of combinations of words-that is, combinations of ideas. Similarly, for him who has a small vocabulary the number of possible combinations of ideas is reduced to a minimum. This faculty for the combination or grouping of ideas may be called general intelligence. Clearly, the vocabulary furnishes us the best basis for the measurement of general intelligence.
The child, immediately upon entering the world, makes his presence known by a cry. This cry is merely a reflex act, induced by the new and strange conditions to which the vocal apparatus of the child is suddenly and rudely subjected. But the cry soon becomes differentiated, assuming different proportions and varied intonations to express different mental states. Later, with the coming of definite ideas we find the entrance of words to express them. The crys and babblings assume a more articulate character. The child's vocabulary is being established.
Speech is not inherited. To some degree it is probably instinctive. The general neural paths favorable to the development of speech are formed in the embryonic stage. But the actual development of speech must begin after birth. Language arises with ideas. Why does the new-born child not talk? The psychological reason is that he is devoid of ideas. He really has nothing to say. There is also a physiological reason. Even though the child had ideas he could not express them vocally, for his speech-apparatus is as yet too imperfectly developed. Not only must the child acquire ideas, but he must also acquire the motor co-ordinations to express those ideas-those otherwise unspoken words. On the cortical surface of the brain, just over and slightly back of each temple, lies a small area known as the convolution of Broca and recognized by psychologists as the speech center. All about this convolution there is a series of highly complex motor centers which utilize secondary motor centers in the face, setting them to work in varying combinations. Next to the motor centers for the face, in the anterior-central gyre, we find the highly differentiated motor centers for the hand (37). Thus we find that the motor centers for the face and for the hand are closely related to those having to do with vocalization. Witness facial expression and the universal use of gestures. An idea, a word, may be expressed by means other than vocal.show more