"The child ignorant of letters wonders at the resources of those who can spell and read, and, in like manner, many obscure natural phenomena are marvelous to man only because of his ignorance. You do not comprehend the fact that sunlight is simply a matter-bred expression, an outburst of interrupted energy, and that the modification this energy undergoes makes it visible or sensible to man. What, think you, becomes of the flood of light energy that unceasingly flows from the sun? For ages, for an eternity, it has bathed this earth and seemingly streamed into space, and space it would seem must have long since have been filled with it, if, as men believe, space contains energy of any description. Man may say the earth casts the amount intercepted by it back into space, and yet does not your science teach that the great bulk of the earth is an absorber, and a poor radiator of light and heat? What think you, I repeat, becomes of the torrent of light and heat and other forces that radiate from the sun, the flood that strikes the earth? It disappears, and, in the economy of nature, is not replaced by any known force or any known motion of matter. Think you that earth substance really presents an obstacle to the passage of the sun's energy? Is it not probable that most of this light producing essence, as a subtle fluid, passes through the surface of the earth and into its interior, as light does through space, and returns thence to the sun again, in a condition not discernible by man?" He grasped my arm and squeezed it as though to emphasize the words to follow. "You have used the term sunshine freely; tell me what is sunshine? Ah! you do not reply; well, what evidence have you to show that sunshine (heat and light) is not earth-bred, a condition that exists locally only, the result of contact between matter and some unknown force expression? What reason have you for accepting that, to other forms unknown and yet transparent to this energy, your sunshine may not be as intangible as the ether of space is to man? What reason have you to believe that a force torrent is not circulating to and from the sun and earth, inappreciable to man, excepting the mere trace of this force which, modified by contact action with matter appears as heat, light, and other force expressions? How can I, if this is true, in consideration of your ignorance, enter into details explanatory of the action that takes place between matter and a portion of this force, whereby in the earth, first at the surface, darkness is produced, and then deeper down an earth light that man can perceive by the sense of sight, as you now realize? I will only say that this luminous appearance about us is produced by a natural law, whereby the flood of energy, invisible to man, a something clothed now under the name of darkness, after streaming into the crust substance of the earth, is at this depth, revivified, and then is made apparent to mortal eye,