organizes this experience must be our problem in the chapters on sensations, ideas, memory, and thinking. Individual differences in human capacity make necessary a treatment of the different types and grades of intelligence, and the compilation of tests for determining these differences. We must also treat of the application of psychology to those fields where a knowledge of human nature is necessary.

Applied Psychology. At the beginning of a subject it is legitimate to inquire concerning the possibility of applying the principles studied to practical uses, and it is very proper to make this inquiry concerning psychology. Psychology, being the science of human nature, ought to be of use in all fields where one needs to know the causes of human action. And psychology is applicable in these fields to the extent that the psychologist is able to work out the laws and principles of human action.

In education, for example, we wish to influence children, and we must go to psychology to learn about the nature of children and to find out how we can influence them. Psychology is therefore the basis of the science of education.

Since different kinds of work demand, in some cases, different kinds of ability, the psychology of individual differences can be of service in selecting people for special kinds of work. That is to say, we must have sometime, if we do not now, a psychology of professions and vocations. Psychological investigations of the reliability of human evidence make the science of service in the court room. The study of the laws of attention and interest give us the psychology of advertising. The study of suggestion and abnormal states make psychology of use in medicine. It may be said, therefore, that psychology, once abstract and unrelated to any practical interests, will become the most useful of all sciences, as it works out its problems and finds the laws of human behavior.

At present, the greatest service of psychology is to education. So true is this that a department has grown up called “educational psychology,” which constitutes at the present time the most important subdivision of psychology. While in this book we treat briefly of the various applications of psychology, we shall have in mind chiefly its application to education.

The Science of Education. Owing to the importance which psychology has in the science of education, it will be well for us to make some inquiry into the nature of education. If the growth, development, and learning of children are all controlled and determined by definite causal factors, then a systematic statement of all these factors would constitute the science of education. In order to see clearly whether there is such a science, or whether there can be, let us inquire more definitely as to the kind of problems a science of education would be expected to solve.

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.

The answer to the fourth question is in part dependent upon the progress in answering the third. Economical methods of training children must be dependent upon the nature of children. But in actual practice, we are trying to find out the best procedure of doing each single thing in school work; we are trying to find out by experimentation. The proper way to teach children to read, to spell, to write, etc., must be determined in each case by independent investigation, until our knowledge of the child becomes sufficient for us to infer from general laws of procedure what the procedure in a particular case should be. We venture to infer what ought to be done in some cases, but generally we feel insecure till we have proved our inference correct by trying out different methods and measuring the results.

Education will not be fully scientific till we have definite knowledge to guide us at every step. What should we teach? When should we teach it? How should we teach it? How poorly we answer these questions at the present time! How inefficient and uneconomical our schools, because we cannot fully answer them! But they are answerable. We can answer them in part now, and we know how to find out the answer in full. It is just a matter of patient and extensive investigation. We must say, then, that we have only the beginnings of a science of education. The problems which a science of education must solve are almost wholly psychological problems. They could not be solved till we had a science of psychology. Experimental psychology is but a half-century old; educational psychology, less than a quarter-century old. In the field of education, the science of psychology may expect to make its most important practical contribution. Let us, then, consider very briefly the problems of educational psychology.

Educational Psychology. Educational psychology is that division of psychology which undertakes to discover those aspects of human nature most closely related to education. These are (1) the original nature of the child—what it is and how it can be modified; (2) the problem of acquiring and organizing experience—habit-formation, memory, thinking, and the various factors related to these processes. There are many subordinate problems, such as the problem of individual differences and their bearing on the education of subnormal and supernormal children. Educational psychology is not, then, merely the application of psychology to education. It is a distinct science in itself, and its aim is the solving of those educational problems which for their solution depend upon a knowledge of the nature of the child.