Matter can not move itself or stop itself.
This is true of all matter that is not alive. You can set yourself in motion, and stop yourself, for you are alive; but common dead matter can do neither. It moves because it is moved, and it stops because it is stopped by something.
How fast the earth moves.
Now the earth is a ball that is always moving. It never stops for an instant, but is all the time rolling on around and around the sun. God a long time ago set it agoing, and it never has been still since. It takes a year for it to go round the sun; and how fast do you think it goes? About 68,000 miles an hour—that is, over a thousand miles every minute. This is two thousand times as fast as the cars go when they are going very fast indeed. What a ride we are taking on this round ball of earth!
Why it does not seem to us to move.
But you will ask why it is that we do not feel any thing of this motion, or know something about it, just as we do about the motion of traveling. The reason of this is very easily seen. Just observe how it is that you know about the motion in traveling. You see trees, houses, fences, etc., as you pass by them. You feel the air as you go through it. If the motion is uneven, you feel it. It is by these things that you know that you are moving along. But as we are carried along on the earth as it goes around the sun, there are none of these things to let us know that we are moving. Every thing goes along with us—trees, houses, fences, and every thing else. We do not go through the air, but the air goes along with us. Then, too, the motion is very even. The earth is not jostled and jarred in its course.
Sometimes, when you are riding in the cars, you hardly seem to move at all, though you may be really going very fast. The reason of this is plain. First, the motion is very even; then the air that is in the car goes along with you, though the air that is outside does not; and the people in the car that you are looking at are going along with you also.
Illustrations from the motion of cars in traveling.
But the moment you look out of the car window you know that the cars are going quite rapidly, because you see that you are going so fast by the trees and houses. So, too, if the cars come to a place where the rails are not so even, the irregular motion lets you know that you are going fast. Sometimes, when you seem to be going along quite moderately, because the rails are so even and the road is so straight, all at once you seem to be twitched along with a very sudden, quick start. It seems to you as if the cars suddenly went a great deal faster, but it is not so. The cars are really moving no faster than before. A turn in the road makes it seem so, because it makes the motion irregular instead of even.
Now, if the motion of the cars were perfectly even, and you did not look out, you would not know that they were moving at all. Just so it is with the earth. Its motion is so even that we do not feel that it moves at all, though it is carrying us two thousand times as fast as the cars carry us when they are going thirty-four miles in an hour.