[A Canticle for Leibowitz] is a curious and original and very serious book, and it will be so satisfactory to the right reader that I think a warning is in order: though the action takes place in the future, and though a space ship takes off on the final page, this should not be confused with what is usually called science fiction. In a way, it is a cautionary tale about man's perennial inhumanity to man, and the invevitable use he will make of scientific means to that end. But even this is not Mr. Miller's gist. What he has really written is a highly imaginative, and basically joyous, celebration of human kind's instinct to keep going, and especially of those members of the race who are not so much discoverers and pathfinders, as preservers and safekeepers, whose instinct is to build and retain a tradition….

In three...