The author links Chaucer's writings with the medieval optical tradition in its various forms (scholastic texts, encyclopedias, exempla, vernacular poetry) both in general cultural terms and through the discussion of specific examples. He shows how the science of optics, or "perspectiva," provides an account of spatial perception, including visual error, and demonstrates how these aspects of optical theory impact on Chaucer's poetry. He provides detailed and sustained analysis of the spatial content of narratives across the range of Chaucer's works, relating them to optical ideas and making use of Lefebvre's theory of the production of space. The texts discussed include the "Book of the Duchess," "House of Fame," Knight's Tale, Miller's Tale, Reeve's Tale, Merchant's Tale, Squire's Tale and "Troilus and Criseyde."