Dante did, however, live in a Europe of substantial literary and philosophical contact with the Muslim world, encouraged by such factors as Averroism ("Averrois, che'l gran comento feo" Commedia, Inferno, IV, 144, meaning "Averrois, who wrote the great comment") and the patronage of Alfonso X of Castile. Of the twelve wise men Dante meets in Canto X of the "Paradiso", Thomas Aquinas and, even more so, Siger of Brabant were strongly influenced by Arabic commentators on Aristotle. Medieval Christian mysticism also shared the Neoplatonic influence of Sufis such as Ibn Arabi. Philosopher Frederick Copleston argued in 1950 that Dante's respectful treatment of Averroes, Avicenna, and Siger of Brabant indicates his acknowledgement of a "considerable debt" to Islamic philosophy.