But the Dominicans were as subtle as they were zealous. They felt that the citadel of Judaism which had held out for so many centuries, could not be carried by storm. They resorted to less crude tactics. With a patience, perseverance, and ingenuity worthy of their high ambition, they devoted themselves to the study of the Hebrew language and literature, their Master Raymund de Peñaforte prevailing upon the Kings of Aragon and Castile to found special colleges for the purpose. The Prophets of the Old Testament had already supplied the apologists of the Church with proofs of the truth of Christianity.[51] The Talmud was now to supply them with fresh proofs of the falsity of Judaism. From the pages of that marvellous compilation of noble thoughts and multifarious absurdity, they culled everything that was likely to reflect discredit on the morality or the intelligence of their adversaries. In this campaign the Dominicans were fortunate enough to enlist the services of renegade Jews, who, after the fashion of renegades, strove to prove their loyalty to the faith they embraced by a bitter persecution of the one they deserted. One of these apostates, Nicolas Donin by name, in 1239 submitted to Pope Gregory IX. a minute indictment of the pernicious book, and induced him to issue Bulls to the Kings of England, Spain, and France, as well as to the bishops in those countries, ordering a general confiscation of the Talmud, and a public enquiry into the charges brought against its contents. The Pope’s instructions, so far as we know, appear to have produced no impression in the first two kingdoms, but in France there reigned Louis IX., known to fame as St. Louis: in mundane affairs a brave, high-minded, just and humane prince; but not far in advance of his age in things celestial. In fact, he possessed all the prejudices of an ordinary mediaeval knight, and more than the superstition of an ordinary mediaeval monk. He was sincerely convinced that the road to heaven lay through Jerusalem. Acting on this conviction, he led the last two Crusades, and laid down his life in the cause of Catholicism; a sacrifice which earned him a place among the saints of the Church. Such a prince could not, without flagrant inconsistency, ignore the Pontiff’s wishes. He, therefore, ordered that a careful search for the suspected book should be made throughout his dominions, that all copies should be seized, and that a public disputation should be held, in which four Rabbis were to take up the challenge thrown down by Donin.