Abstract

This paper inquires into how the new techniques of 14th-century physics, especially the doctrines of the maxima and minima of powers and the latitudes of forms, were applied to the issue of propagation of light. The focus is on several Prague disputed questions, originating between 1377 and 1409, dealing with whether illumination has infinite or finite reach and whether illumination’s intensity remains constant (uniformis) or is rather uniformly decreasing (uniformiter difformis). These questions are contextualised through examination of Oxford, Paris, and Prague sources of the era (John Dumbleton, John Buridan, Nicole Oresme, Albert of Saxony, Henry of Langenstein, John of Holland) to construct a fresh survey of late medieval theories of light. Along the way, the discovery of a hitherto unknown Prague disputation from the 1370s is announced, and new evidence for the dating and Central European dissemination of Jacobus de Sancto Martino’s De latitudinibus formarum and Nicole Oresme’s Questiones super Geometriam is uncovered.