Book excerpt: Astronomy is one of the most prominent and perplexing features of Dante's Divine Comedy. In the final rhyme of the poem's three parts, and in scores of descriptions and analogies, the stars are an intermediate goal and a constant point of reference for the spiritual journey the poem narrates. This book makes a sustained analysis of Dante's use of astronomy, not only in terms of the precepts of medieval science but also in relation to specific moral, philosophical, and poetic problems laid out in each chapter.For Dante, Alison Cornish says, the stars offer optical representations of invisible realities, from divine providence to the workings of the human soul. Dante's often puzzling celestial figures call attention to the physical world as a scene of reading in which visible phenomena are subject to more than one explanation, Cornish contends. The poetry of Dante's astronomy, as well as its difficulty, rests on this imperative of interpretation. Reading the stars, like reading literature, is an ethical undertaking fraught with risk, not just an exercise in technical understanding. Cornish's book is the first guide to the astronomy of Dante's masterpiece to encompass both ways of reading his work.