was a posthumous scholastic accolade.) A caustic cleric named Roger Bacon is recorded speaking before the king at Oxford in 1233. In 1237 or at some point in the following decade, he accepted an invitation to teach at the University of Paris. While there, he lectured on Latin grammar, Aristotelian logic, arithmetic, geometry, and the mathematical aspects of astronomy and music. His faculty colleagues included Robert Kilwardby, Albertus Magnus, and Peter of Spain, the future Pope John XXI. The Cornishman Richard Rufus was a scholarly opponent. In 1247 or soon after, he left his position in Paris. As a private scholar, his whereabouts for the next decade are uncertain but he was likely in Oxford –1251, where he met Adam Marsh, and in Paris in 1251. He seems to have studied most of the known Greek and Arabic works on optics (then known as "perspective", ). A passage in the states that at some point he took a two-year break from his studies. By the late 1250s, resentment against the king's preferential treatment of his émigré Poitevin relatives led to a coup and the imposition of the Provisions of Oxford and Westminster, instituting a baronial council and more frequent parliaments. Pope Urban IV absolved the king of his oath in 1261 and, after initial abortive resistance, Simon de Montfort led a force, enlarged due to recent crop failures, that prosecuted the Second Barons' War. Bacon's own family were considered royal partisans: De Montfort's men seized their property and drove several members into exile. In 1256 or 1257, he became a friar in the Franciscan Order in either Paris or Oxford, following the example of scholarly English Franciscans such as Grosseteste and Marsh. After 1260, Bacon's activities were restricted by a statute prohibiting the friars of his order from publishing books or pamphlets without prior approval. He was likely kept at constant menial tasks to limit his time for contemplation and came to view his treatment as an enforced absence from scholarly life. By the mid-1260s, he was undertaking a search for patrons who could secure permission and funding for his return to Oxford. For a time, Bacon was finally able to get around his superiors' interference through his acquaintance with Guy de Foulques, bishop of Narbonne, cardinal of Sabina, and the papal legate who negotiated between England's royal and baronial factions. In 1263 or 1264, a message garbled by Bacon's