There was never a time when the world began, because it goes round and round like a circle, and there is no place on a circle where it begins. Look at my watch, which tells the time; it goes round, and so the world repeats itself again and again. But just as the hour-hand of the watch goes up to twelve and down to six, so, too, there is day and night, waking and sleeping, living and dying, summer and winter. You can't have any one of these without the other, because you wouldn't be able to know what black is unless you had seen it side-by-side with white, or white unless side-by-side with black.