How quickly we get where no step can be taken! We cannot step off the planet, though we may step off from every object on its surface. There is no heat in sunlight till it reaches the earth; heat is an experience of our bodies, and beings on the remotest planets, if there are any, may and must receive adequate heat, and beings on Mercury and Venus no more. Terrestrial physics and celestial physics must be the same, and yet celestial mechanics find no place on the surface of our planet. The laws of the cosmos bring to naught our mundane conceptions. Where are up and down, east and west, over and under, out in sidereal space? We balk at perpetual motion, yet in the heavens, and in the interior of matter, behold perpetual motion! Behold motion without friction and energy without waste or dissipation! On the earth every visible body rests on some other body, everything has a beginning and an end, but where is the beginning or the ending of the cosmos? Where, then, in this quest do we touch bottom? Nowhere. There is no bottom. Only measurable, finite things have bottoms and bounds. The immeasurable, the Infinite, is over us and under us, and our lives are like sparks against the night. But, just as we live in the heavens and do not know it, so we live and move and have our being in the Eternal. It is not afar off; it is here; we are a part of it, and as inseparable from it as from gravity. We are not like beings who have moved into a house, made and furnished and provisioned in anticipation of our coming. We are creatures born in a house, or amid an environment to which we must slowly and more or less painfully fit ourselves. We are the consequent, not the antecedent. In a different world we should have been differently constituted. In a bigger world no doubt our bodies would have been bigger and our strength greater; with less or with more oxygen in the air, no doubt our lungs would have been different. With less light no doubt our eyes would have been larger, and with more light they would probably have been smaller. We do not feel the pressure of the atmosphere, but make the pressure more or less, and we are at once disturbed. The deep-sea fishes fairly explode when brought to the surface, and no doubt the surface fishes would be crushed in the deep sea bottoms. Just as we adjust our flying machines to the tenuity of the air, and our oversea and undersea boats to the density and weight of the water, so Nature adjusts her organisms to their environment.