This yearly journey round the sun which the earth takes is a long one, but so swiftly does it move that it may be said rather to fly than to wander. Shut your eyes and count "One," "two," "three," "four," "five"; in this little moment of time the earth will have got over a hundred miles of its journey. You see it flies along faster than any bird; and what a noiseless flight it is! How is it that we do not feel it moving? Ah, you must remember that the earth carries _you_ along with it; you know nothing about the rapid journey, and yet you are a traveller in spite of yourself--a traveller round the sun. All the planets, like our earth, move round the sun, and are kept in their places by means of a wonderful power which we cannot see, but which is one of those "laws of nature," as the rules which God has made for His great universe are sometimes called, about which I told you that they never alter. It is a law, or rule, that, in the world around us, "the same causes always produce the same effects." If you think a little about this, it will become plain to you that it is so, and if you observe carefully you will see that this rule is the same in connection with the smallest as well as the greatest things; if it ever seems that it is not so, be sure that this is only because you do not yet know all about what you have been observing. And now learn a little about the beautiful rule by which the planets are kept in their places. Two hundred years ago, Sir Isaac Newton discovered that everything in the universe attracts or draws every other thing to itself, and this power or attraction he called "the force of gravitation." I cannot do much more than tell you the name of this "law," but you will learn more about it one day I hope, and see how simple and yet how wonderful it is. An astronomer of our own day says, in his _Story of the Heavens_, that there are "grounds for believing that the law of gravitation is obeyed throughout the length, the breadth, the depth, and the height of the entire universe," and a little observation and thought will enable you to see something of its working in the world around us.