Written in 1965. Chapter on the origin of the moon is amusing in hindsight. He spends about a page and a half explaining George Darwin's 1898 theory that the moon broke away from the earth, and concludes "But nobody believes any of this anymore. There is no way in which a large piece can break away from a planet without causing more than comparitively minor damage to the rest of it. The idea that the moon might be a child of the earth is as obsolete as an idea can be." Well, guess what the current theory of the origin of the moon is?