I trust that by this time I have said enough to convince the reader both of the truth and of the importance of my thesis. The two questions, first, that of the possible extent of our powers; and, second, that of the various avenues of approach to them, the various keys for unlocking them in diverse individuals, dominate the whole problem of individual and national education. We need a topography of the limits of human power, similar to the chart which oculists use of the field of human vision. We need also a study of the various types of human being with reference to the different ways in which their energy-reserves may be appealed to and set loose. Biographies and individual experiences of every kind may be drawn upon for evidence here.[4] [1] This was the title originally given to the Presidential Address delivered before the American Philosophical Association at Columbia University, December 28, 1906, and published as there delivered in the _Philosophical Review_ for January, 1907. The address was later published, after slight alteration, in the _American Magazine_ for October, 1907, under the title "The Powers of Men." The more popular form is here reprinted under the title which the author himself preferred. [2] "The Energies of Men." _Philosophical Review_, vol. xvi, No. 1, January, 1907. [Cf. Note on p. 229.] [3] "Tour in England, Ireland, and France," Philadelphia, 1833, p. 435. [4] "This would be an absolutely concrete study . . . The limits of power must be limits that have been realized in actual persons, and the various ways of unlocking the reserves of power must have been exemplified in individual lives . . . So here is a program of concrete individual psychology . . . It is replete with interesting facts, and points to practical issues superior in importance to anything we know." _From the address as originally delivered before the Philosophical Association_; See xvi. _Philosophical Review_, 1, 19. XI THE MORAL EQUIVALENT OF WAR[1]