This contribution offers a description of codex Plut. 17 sin. 8 from the Laurentian Library, a manuscript that may have been in Florence (possibly in the library of Santa Croce) since the late 13th century and which contains numerous texts on the science of perspectiva and on physical and spiritual light. Particular attention is devoted to the works of John Peckham (De numeris misticis, Perspectiva communis, Tractatus de perspectiva, Quaestiones) and Bartolomeo da Bologna (De luce, Quaestiones) transmitted by the miscellany. These texts testify to the close connection between optics and theology, and to the interest in such disciplines shown by friar minors (as well as other clerics) in the mid-13th century. Following an in-depth analysis of each quire and of some marginal annotations, the paper discusses the editorial project that may lie at the basis of the miscellany, and its potential readers, ultimately presenting some hypotheses with regard to the role played by the Franciscan preacher Servasanto da Faenza in relation to this «publishing venture».