When a person knows how to speak, the conditioning proceeds in the opposite direction to that which operates in understanding what others say. The reaction of a person who knows how to speak, when he notices a cat, is naturally to utter the word “cat”; he may not actually do so, but he will have a reaction leading towards this act, even if for some reason the overt act does not take place. It is true that he may utter the word “cat” because he is “thinking” about a cat, not actually seeing one. This, however, as we shall see in a moment, is merely one further stage in the process of conditioning. The use of single words, as opposed to sentences, is wholly explicable, so far as I can see, by the principles which apply to animals in mazes. Certain philosophers who have a prejudice against analysis contend that the sentence comes first and the single word later. In this connection they always allude to the language of the Patagonians, which their opponents, of course, do not know. We are given to understand that a Patagonian can understand you if you say “I am going to fish in the lake behind the western hill”, but that he cannot understand the word “fish” by itself. (This instance is imaginary, but it represents the sort of thing that is asserted.) Now it may be that Patagonians are peculiar--indeed they must be, or they would not choose to live in Patagonia. But certainly infants in civilized countries do not behave in this way, with the exception of Thomas Carlyle and Lord Macaulay. The former never spoke before the age of three, when, hearing his younger brother cry, he said, “What ails wee Jock?” Lord Macaulay “learned in suffering what he taught in song”, for, having spilt a cup of hot tea over himself at a party, he began his career as a talker by saying to his hostess, after a time, “Thank you, Madam, the agony is abated”. These, however, are facts about biographers, not about the beginnings of speech in infancy. In all 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 grownups, 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.