Schiller, even as a boy, “felt that without diligence no mastery can be won.” Halley once asked Newton how he had made his marvellous discoveries in the physical realm. “By always thinking about them,” was his reply. Thus the record might be continued down to the Edisons and Bergsons and Debussys of to-day. Quite evidently, what happens is that the perpetual concentration of attention on some one problem or set of problems, not merely deposits in the subconscious an exceptional wealth of material, but also favours the emergence of the results of its manipulation of that material. Just as, in the case of the ordinary man, it is only when he is intensely interested in, say, the detection of an error in book-keeping, that he is likely to have the cause of that error made plain to him by a sudden “happy thought,” or through the medium of a dream. It may, then, be stated as a well-established fact that intense interest plus persistent effort is the prime essential to the highest success in any sphere of human activity. Of importance, also, is the fact that, as a general thing, the “set” of a man’s mind, the direction which his interest most readily takes, is indicated more or less clearly in the first years of life. This is proved not only by the early lives of the world’s most eminent men and women, but also by the results of careful statistical investigations into the life histories of “average” people. Especially impressive are the findings of an inquiry carried out not long ago by that well-known American psychologist, Edward L. Thorndike, and reported by him in _The Popular Science Monthly_, vol. lxxxi (1912). Professor Thorndike submitted to one hundred third year students in Columbia College, Barnard College, and Teachers’ College, New York, a list of subjects of study, including mathematics, history, literature, science, drawing, and such hand-work as carving, carpentering, gardening, etc. Each student was required to fill in a tabular blank showing the order in which the various subjects were of greatest interest to that particular student: (1) during the last three years of elementary school attendance, (2) during the high school period, and (3) at the time of the investigation. Blanks were also to be filled indicating the student’s judgment as to his or her ability in each of the respective subjects during the period covered by the inquiry. From the statistics thus gathered two things stood out clearly. No fewer than 60 per cent. of the students made returns showing that the subjects which appealed to them most strongly in their college work were the subjects that had most interested them in early life; and an even closer correspondence (65 per cent.) was shown between intensity of interest and intellectual ability. Professor Thorndike then extended his investigation to include two hundred other individuals, and obtained virtually the same results.