Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. The material found in this book is taken from the lec tures given at my elementary course at the department of pedagogics of the New York University. This course is primarily intended for those who are occupying themselves with problems of education and psychology. But as it is impossible to talk about the normal individual without show ing what would happen to a child if subjected to a peculiar or special kind of environment, I have given illustrative cases from abnormal spheres as well as brief, in no way technical, descriptions of some forms of mental derange ments. I have also tried to avoid technical expressions as much as possible, and have not taken the trouble to clutter this volume with a lot of references, which a book intended for professional people would necessarily demand, but any one knowing of my activities realizes that all my work is built on Prof. Freud’s foundations, and are referred to his works for more detailed and more technical information. Mr. Sydney M. Frankel, one of my former students, has given me very valuable suggestions, and relieved me of the task of indexing this book. I am very much indebted to him.