What is light doing in space? That has greatly puzzled all philosophers. Without question there is inexpressible power. It is seen in velocity. But what is it doing? The law of conservation of force forbids the thought that it can be wasted. On the earth its power long ages ago was turned into coal. The power was reservoired in mountains ready for man. It is so great that a piece of coal that weighs the same as a silver dollar carries a ton's weight a mile at sea. But what is the thousand million times more light than ever struck the earth doing in space? That is among the things we want to find out when we get there. There will be ample opportunity, space, time, and light enough. It is biblically asserted and scientifically demonstrable that space is full of causes of sound. To anyone capable of turning these causes to effects this sound is not dull and monotonous, but richly varied into songful music. Light makes its impression of color by its different number of vibrations. So music sounds its keys. We know the number of vibrations necessary for the note C of the soprano scale, and the number that runs the pitch up to inaudibility. We know the number of vibrations of light necessary to give us a sensation of red or violet. These, apprehended by a sufficiently sensitive ear, pour not only light to one organ, but tuneful harmonies to another. The morning stars do sing together, and when worlds are gone, and heavy ears of clay laid down, we may be able to hear them Singing as they shine, "The hand that made us is divine." There are places where this music is so fine that the soft and soul-like sounds of a zephyr in the pines would be like a storm in comparison, and places where the fierce intensity of light in a congeries of suns would make it seem as if all the stops of being from piccolo to sub-bass had been drawn. No angel flying interstellar spaces, no soul fallen overboard and left behind by a swift-sailing world, need fear being left in awful silences.