From the moment children first speak - first attach a sound to an object or a person - language plays a significant and central part in their development. Their speech is, of course, a means of communication, but the stress in this book is on the importance of speech, not to their listeners, but to themselves. It shows, for example, that much of children's behaviour consists in doing what they have told themselves to do; that the world they see and act in is a world largely called into existence by words of their own speaking; that it is by speech, from infancy, that they make sense of their environment.