In this chapter we shall gather together and amplify considerations that have already been advanced, in various passages of the preceding pages, concerning the relation of _action to thought_. We shall follow, though not with exactness, the order of development in the unfolding human being. § 1. _The Early Stage of Activity_ [Sidenote: 1. The baby's problem determines his thinking] The sight of a baby often calls out the question: "What do you suppose he is thinking about?" By the nature of the case, the question is unanswerable in detail; but, also by the nature of the case, we may be sure about a baby's chief interest. His primary problem is mastery of his body as a tool of securing comfortable and effective adjustments to his surroundings, physical and social. The child has to learn to do almost everything: to see, to hear, to reach, to handle, to balance the body, to creep, to walk, and so on. Even if it be true that human beings have even more instinctive reactions than lower animals, it is also true that instinctive tendencies are much less perfect in men, and that most of them are of little use till they are intelligently combined and directed. A little chick just out of the shell will after a few trials peck at and grasp grains of food with its beak as well as at any later time. This involves a complicated coördination of the eye and the head. An infant does not even begin to reach definitely for things that the eye sees till he is several months old, and even then several weeks' practice is required before he learns the adjustment so as neither to overreach nor to underreach. It may not be literally true that the child will grasp for the moon, but it is true that he needs much practice before he can tell whether an object is within reach or not. The arm is thrust out instinctively in response to a stimulus from the eye, and this tendency is the origin of the ability to reach and grasp exactly and quickly; but nevertheless final mastery requires observing and selecting the successful movements, and arranging them in view of an end. _These operations of conscious selection and arrangement constitute thinking_, though of a rudimentary type. [Sidenote: Mastery of the body is an intellectual problem] Since mastery of the bodily organs is necessary for all later developments, such problems are both interesting and important, and solving them supplies a very genuine training of thinking power. The joy the child shows in learning to use his limbs, to translate what he sees into what he handles, to connect sounds with sights, sights with taste and touch, and the rapidity with which intelligence grows in the first year and a half of life (the time during which the more fundamental problems of the use of the organism are mastered), are sufficient evidence that the development of physical control is not a physical but an intellectual achievement. [Sidenote: 2. The problem of social adjustment and intercourse]