No one knew better than Maxwell, that his speculations on matter and electricity were theories, and that what he was offering to science were not definite explanations, but possible hypotheses. He has emphasized this himself over and over again. This inability of the human intellect at the present moment to solve all the questions that its inquiring spirit can evoke, did not keep him from investigating and following up his investigations by mathematical deductions and mechanical suggestions just as far as possible. He had the same attitude of mind toward the great problems of man's relation to his fellow-man, to the universe, and to a hereafter. While he felt that he could not solve the problems entirely, he felt also that his reasoning was quite sufficient to enable him to get a little nearer to the heart mystery of them and to understand something of their significance. In his later years, the question of the existence of pain and suffering in the world had, because of Darwin's attitude towards them and his declaration that since he was unable to understand them they carried him away from the thought of a beneficent Creator, attracted much attention. We have an essay of Clerk Maxwell's, then, on "Aspects of Pain," in which he discusses particularly pain as discipline. It is, of course, the old story, that men rise on stepping-stones of their dead selves, and that the successive deaths of self represent a triumphant progress, but it comes with a new vigor from this great scientist. We all know that it is the man who has suffered who is able to do things, and we are all well aware that the man who has lived in comfort all his life is almost sure to be lacking in character when a great crisis comes upon him. Indeed, as Clerk Maxwell re-states it, this is such a commonplace that one wonders why the problem of pain should have seemed so hard to understand. There is an essay of his, also, on "Science and Free Will," which seems to deserve special notice. He has no illusions with regard to determinism. He is perfectly sure that he is free and that the great majority of men around him do or do not things as they choose. He points out that science makes for determinism only if one takes a very narrow view of it. Free will is not only compatible with scientific thinking, but it represents what would be expected as a culmination of the significance of life. In a word, Clerk Maxwell wrote as suggestively with regard to the great problems of human life as with regard to the physical nature around him that claimed so much of his interest. He was a true natural philosopher, and his interests were not limited merely to the lower orders of beings.