517. How do we know that objects reflect light in every direction?
Because if we prick a hole in a card with a pin, and then look through that small hole upon a landscape, we can see some miles of country, and some thousands of objects; every part of every object throughout the whole scene, must have sent rays of light the small hole pricked in the card.
"Such knowledge is too wonderful for me; it is high, I cannot attain unto it."—Psalm cxxxix.
At one extremity of the landscape, viewed through the hole in the card, there may be a forest of trees; in the distance there may be hills bathed in golden light, and overhung with glittering clouds; in the mid-distance there may be a river winding its course along, as though it loved the earth through which it ran, and wished, by wandering to and fro, to refresh the thirsty soil; in the foreground may be a church, covered by a million ivy leaves; and grouping towards the sacred edifice may be hundreds of intending worshippers, old and young, rich and poor; flowers may adorn the path-ways, and butterflies spangle the air with their beauties; yet every one of those objects—the forest, the hills, the clouds, the river, the church, the ivy, the people, the flowers, the butterflies—must have sent rays of light, which found their way through the little hole in the card, and entered to paint the picture upon the curtain of the eye.
This is one of the most striking instances that can be afforded of the wonderful properties of light, and of the infinitude of those luminous rays that attend the majestic rising of the sun. Not only does light fly from the grand "ruler of the day" with a velocity which is a million and a half times greater than the speed of a cannon-ball, but it darts from every reflecting surface with a like velocity, and reaches the tender structure of the eye so gently that, as it falls upon the little curtain of nerves which is there spread to receive it, it imparts the most pleasing sensations, and tells its story of the outer world with a minuteness of detail, and a holiness of truth. Philosophers once sought to weigh the sunbeam; they constructed a most delicate balance, and suddenly let in upon it a beam of light; the lever of the balance was so delicately hung that the fluttering of a fly would have disturbed it. Everything prepared, the grave men took their places, and with keen eyes watched the result. The sunbeam that was to decide the experiment had left the sun eight minutes prior to pass the ordeal. It had flown through ninety-five millions of miles of space in that short measure of time, and it shot upon the balance with unabated velocity: but the lever moved not, and the philosophers were mute.