Projected color saturates our world of images and screens, leading to a dissociation of color from material realities through its cultural attachment to light and the efflorescence of optics. Under these conditions, it is difficult to imagine a past where color was an eminently material, cultural, and social object. The aim of the book is to illustrate how color has been a central "cultural object" within art history, a fact first elucidated through an examination of the historical debates on color in language, theology, science, and philosophy. Following the overview of medieval aesthetical debates, the author concentrates on two pivotal case studies which span the twelfth and thirteenth centuries: the basilica of Saint-Denis and the Cathedral of Lincoln. In both of these, he focuses on the art of stained glass, a revolutionary medium that blurs the boundaries between color, materiality, and light. This beautifully illustrated volume reflects the medieval notion of color, which played a fundamental and groundbreaking role at the crossroads of aesthetic, intellectual, and theological issues.