Let me here interrupt myself for a moment to say that the problem which we are attacking, so far from being solved, has heretofore hardly even been stated. And this is due to the fact that moral instruction has been thus far almost entirely in the hands of persons whose chief interest was religious, and who, whatever their good intentions might be, were hardly qualified to look at the subject from the educator's point of view. The work of breaking ground in the matter of moral instruction has still to be done. As to the selective principle which I have in view I feel a certain confidence in its correctness; but I am aware that the applications of it will doubtless require manifold amendment and correction, for which purpose I invoke the experience and honest criticism of my fellow-teachers. This being understood, I venture to ask your attention to the following considerations: The life of every human being naturally divides itself into distinct periods--infancy, childhood, youth, etc. Each period has a set of interests and of corresponding duties peculiar to itself. The moral teaching should be graded according to periods. The teaching appropriate to any period is that which bears upon the special duties of that period. To illustrate, the ethics of childhood may be summarized as follows: The personal duties of a child are chiefly the observance of a few simple rules of health and the curbing of its temper. It owes social duties to parents, brothers and sisters, and kinsfolk, to its playmates, and to servants. The child is not yet a citizen, and the ethics of politics, therefore, lie far beyond its horizon; it does not yet require to be taught professional ethics, and does not need to learn even the elements of intellectual duty, because its energies are still absorbed in physical growth and play. The duties of childhood can be readily stated. The peculiar duties of the subsequent stages of development, for instance, of middle life and old age, are complex, and not so easy to define. But I believe that the attempt to describe them will throw light on many recondite problems in ethics.