The moon, unlike the sun, has no light or heat of her own to give out. She shines merely by reflected light. Rays of sunlight falling upon her, rebound thence, and find their way earthward. This giving of reflected light is not a matter all on one side. We yield to the moon a great deal more than she yields to us. Full earth, seen from the moon, covers a space thirteen times as large as full moon seen from earth. Perhaps you may have noticed, soon after new moon, when a delicate crescent of silver light shows in the sky, that within the said crescent seems to lie the body of a round, dark moon, only not perfectly dark. It shows a faint glimmer. That glimmer is called earth-shine. The bright crescent shines with reflected sunlight. The dim portion shines with reflected earth-light. What a journey those rays have had! First, leaving the sun, flashing through ninety-three millions of miles to earth, rebounding from earth and flashing over two hundred and forty thousand miles to the dark shaded part of the moon, then once more rebounding and coming back, much wasted and enfeebled, across the same two hundred and forty thousand miles, to shine dimly in your eyes and mine. The popular description of this particular view of the moon is “the old moon in the arms of the new.” Now about the _phases_ of the moon; that is, her changes from “new” to “full,” and back again to “new.” If the moon were a starlike body, shining by her own light, she would always appear to be round. But as she shines by reflected sunlight, and as part of her bright side is often turned away from us, the size and shape of the bright part seem to vary. For, of course, only that half of the moon which is turned directly towards the sun is bright. The other half turned away is dark, and can give out no light at all, unless it has a little earth-shine to reflect. As the moon travels round the earth, she changes gradually from new to full moon, and then back to new again. “New moon” is when the moon, in her orbit, comes between the sun and the earth. The half of her upon which the sun shines is turned away from us, and only her dark side is towards us. So at new moon she is quite invisible. It is at new moon that an eclipse of the sun takes place, when the moon’s orbit carries her in a line precisely between sun and earth. Passing onwards round the earth, the moon, as we get a little glimpse of her shining side, first shows a slender sickle of light, which widens more and more till she reaches her first quarter. She is then neither between earth and sun, nor outside the earth away from the sun, but just at one side of us, passing over the earth’s own orbit. Still, as before, half her body is lighted up by the sun. By this time _half_ the bright part and _half_ the dark part are turned towards us; so that, seeing the bright quarter, we name it the “first quarter.”