Ovid's Latin epic of transformation: humans become animals, plants, stars, rivers; the gods pursue and rape and punish; everything changes, nothing is lost. Written around the time of Christ, it became the Middle Ages' and Renaissance's handbook of classical mythology. The poem moves restlessly from tale to tale, linked by the theme of change, and the cumulative effect is of a world in perpetual flux. Shakespeare, Milton, and countless others drew on it. It remains the greatest compendium of ancient myth.