There are four main questions which the science of education must solve: (1) What is the aim of education? (2) What is the nature of education? (3) What is the nature of the child? (4) What are the most economical methods of changing the child from what it is into what it ought to be? The first question is a sociological question, and it is not difficult to find the answer. We have but to inquire what the people wish their children to become. There is a pretty general agreement, at least in the same community, that children should be trained in a way that will make them socially efficient. Parents generally wish their children to become honest, truthful, sympathetic, and industrious. It should be the aim of education to accomplish this social ideal. It should be the aim of the home and the school to subject children to such influences as will enable them to make a living when grown and to do their proper share of work for the community and state, working always for better things, and having a sympathetic attitude toward neighbors. Education should also do what it can to make people able to enjoy the world and life to the fullest and highest extent. Some such aim of education as this is held by all our people. The second question is also answered. Psychological analysis reveals the fact that education is a process of becoming adjusted to the world. It is the process of acquiring the habits, knowledge, and ideals suited to the life we are to live. The child in being educated learns what the world is and how to act in it--how to act in all the various situations of life. The third question--concerning the nature of the child--cannot be so briefly answered. In fact, it cannot be fully answered at the present time. We must know what the child's original nature is. This means that we must know the instincts and all the other inherited capacities and tendencies. We must know the laws of building up habits and of acquiring knowledge, the laws of retention and the laws of attention. These problems constitute the subject matter of educational psychology, and at present can be only partially solved. We have, however, a very respectable body of knowledge in this field, though it is by no means complete.