Newton found the support that holds the earth to the sun and the moon to the earth, but there was no visible cable, no mighty grooves in which the poles of the earth’s axis spin. There was nothing to see, and yet his mind discovered an invisible link that fastens every particle of matter in the universe to every other particle, however remote. One fact after another has forced the scientist to-day to draw upon an invisible world of ether for his explanations of a vast number of the things that appear. Gravitation, electrical phenomena, light and color vision, and, perhaps, the very origin of matter, are due, his mind sees, to the presence of this extraordinary world within, or behind, the world we see. One of the greatest advances that has ever been made in the progress of medicine was made through the discovery of invisible microbes as the cause of contagious and infectious diseases. The ancients had also believed the cause of many diseases to be the presence of invisible agents, which they called “demons,” but they could hit upon no way of _finding_ the “demons” or of banishing them. The scientific physician “sees” the invisible microbe and he “sees” what will put this enemy _hors de combat_. The study of philosophy is chiefly the cultivation of the power to see the invisible. Pythagoras is said to have required a period of a year of silence as an initiation into the business of philosophy—because there was nothing to talk about until the beginner had learned how to see the invisible! The great realities to which the philosopher is dedicated are not things to be found, even with microscopes or telescopes. Nobody is qualified to enter the philosophical race at all—even for the hundred-yard dash—unless in the temporal he can see the eternal, and in the visible the invisible, and in the material the spiritual. There can be no artistic creation until some one comes who has “the faculty divine” to see “The gleam, The light that never was, on sea or land.” Such artistic creations must not be unreal. On the contrary, they must be more real than the scenes we photograph or the factual events we describe. They must present to us something that is in all respects _as it ought to be_. The artist, the poet, the musician succeed in making some object, or some character, or some series of events or sounds raise us above our usual restraints of space and time and imperfection and for a moment give us a glimpse of something eternal.