All of Heinlein's novels in the juvenile series deal with the conquest of space and the future of humankind. In contrast to the novels of many of his contemporaries and, indeed, to his own later works, these books are full of optimism. Human inventiveness and courage overcome the threat of the loathsome wormfaces and even triumph in the face of the coldly objective galactic judges. Heinlein is not blindly optimistic, however. Kip and Peewee manage to bargain for a probationary period during which humankind will have a chance to rid itself of its worst faults, which are declared to be violence, a tendency toward self-destruction, and excessive sentimentality.

Heinlein is implicitly critical of the American educational system. He attacks schools for failing to challenge the brightest students. Kip's school is so bad, in fact, that he is virtually selftaught. Under the guidance of his father, he...