Towards the end of his life, Fisher was to remark that of all the controversies in which he had become embroiled, none had cost him more effort than that over Henry VIII's marriage to Catherine of Aragon. In total, he reckoned he had written seven or eight books on it – which may well have been an underestimate. This certainly represented in quantity and probably also in quality a more significant contribution to the debate than that of any other single individual. Although several of these books are lost, four are known to survive, and we can deduce a fair amount about the contents of another and the outline of a further two. The examination of the arguments he developed in this series of treatises provides the basis of this chapter. But besides an immense contribution to the literature of the divorce, Fisher also played a central, though not a controlling, part in the opposition to the divorce in English academic and ecclesiastical circles. There is a certain similarity here to his part in the English campaign against Luther: leadership by example rather than by the overt exercise of authority. It is remarkable how many of the English opponents of the divorce, like the English opponents of Luther, were friends or clients of the bishop of Rochester. The attitude of his friends in Cambridge did not escape the attention of the king's commissioners when with some difficulty they extracted from the university in 1530 a judgment in favour of the king.