The Rime petrose, Dante's powerful lyrics about a woman as beautiful and as hard as a precious stone, are generally acknowledged to be an important moment in his stylistic development. In this first full-length investigation of the poetics of the petrose and of their relation to the Divine Comedy, Durling and Martinez uncover much new material, especially from medieval science (astrology and mineralogy), philosophy, and theology. The authors argue that the Rime petrose represent a major turning point in Dante's conception of a "microcosmic poetics" that became the fundamental mode of the Commedia. They demonstrate how Dante here attempts his first full account of his relation to the universe as a whole. This work offers many new insights into the intrinsic significance of these remarkable poems and their place in Dante's developmentespecially far-reaching are the implications for the interpretation of the Divine Comedy. The book will be of interest not only to students of Dante but also to intellectual historians, historians of science, students of poetics and poetic theory, and to all those interested in medieval literature.