Under the cover of a standard medieval romance, Chaucer’s Knight’s Tale is a grim and astrologically-rich contemplation of human passion, fortune, and destiny. This article ponders the purposes of the Knight’s Tale’s uses of astrology and astrological symbolism in the context of these larger issues. Why do gods and humans take on qualities of astrology’s planets? Why is so much timing for the action according to planetary hours and days? Of particular note is the poet’s presentation of “Duc” Theseus and his planetary symbolism. These issues also allow us to understand better the tie between the Tale and its narrator.