THIS BOOK OF EARTHS began years ago, as a collection--maps of the Earth, the Moon, the heavens. For it occurred to me, not long ago, that it would be "fun" to put them all together, and many others with them, chosen to fill in the gaps of the original group. Luckily for the fun of it, the search about to begin would not be limited to what we know about the Earth, else it would have ended before it began; for we live in a universe of which we know little, and on a planet of which we know perhaps less. It would include not only what we know, or think to-day we know, but also anything that has been believed or felt or no more than "guessed" to be the picture of the Earth and its place in the universe.