When one takes account of the scale and range of Aquinas’s achievements it becomes clear why he deserves to be described as the greatest of the mediaeval philosopher-theologians, for he was the first thinker of the high mediaeval period to work out in detail the new synthesis between Catholicism and philosophy. It is sometimes supposed that this just meant ‘Christianizing’ Aristotle. Even were that the limit of his achievement it would have been considerable, but in fact he went further. For while he opposed unquestioning appeals to authority, he believed in the idea of cumulative philosophical and religious wisdom and sought to integrate Neoplatonist, Augustinian and Anselmian ideas, as well as Aristotelian ones, with scripture, patristic teaching and evolving Catholic doctrine.