The stars were closed to Max Jones. To get into space you either needed connections, a membership in the Guild, or a whole lot more money than Max, the son of a widowed, poor mother, was every going to have. What Max does have going for him are his uncle's prized astrogation manuals - book on star navigation that Max literally commits to memory word for word, equation for equation. From the First Golden Age of Heinlein, this is the so-called juvenile (written, Heinlein always claims, just as much for adults) that started them all and made Heinlein a legend for multiple generations of readers.