Sixtus IV, in the bull of November 1, 1478, empowered Ferdinand and Isabella to appoint, as inquisitors, three bishops or other worthy men, priests either regular or secular, over forty years of age, God-fearing, of good character and record, masters or bachelors of theology or licentiates of canon law. The prescription as to the minimum age was as old as the Council of Vienne, in 1312, and had become a matter of course; the rest was as well-chosen a definition of the requisite qualities as perhaps could be expressed in general terms, considering the temper of the age and the work to be performed.[646] So, in 1483, when Sixtus, under the influence of Cardinal Borgia, desired to get rid of Inquisitor Gualbes, he asked Ferdinand to replace him with some master of theology who had the fear of God and was eminent for his virtues.[647] The only inquisitors that Spain had known were Dominicans and, although they were not specified, it seemed to be a matter of course that the Inquisition should remain in their hands, but Ferdinand, in his struggle with Sixtus for the control of the Aragonese Inquisition, had encountered the obstacle of the obedience due by the friars to their General, who of course was a creature of the curia. He was resolved to organize the Inquisition to suit himself, which explains why Torquemada, in his Instructions of December 6, 1484, simplified the formula of qualifications to _letrados_ (either lawyers or men of university training) of good repute and conscience, the fittest that could be had.[648] This did not even require the inquisitor to be an ecclesiastic, except in so far as there were comparatively few letrados of the time who were not in orders. When Innocent VIII renewed the commission of Torquemada, February 3, 1485, it empowered him to appoint as inquisitors fitting ecclesiastics, learned and God-fearing, provided they were masters of theology or doctors or licentiates of laws, or cathedral canons or holding other church dignities, but, while this was repeated in a subsequent bull of March 24, 1486, it was simplified, in another clause, into ecclesiastics of proper character and learning, not less than thirty years of age.[649] This reduction in the age limit was retained by Alexander VI, in the commissions issued to Deza, November 24, 1498 and September 1, 1499, when the requisite of being an ecclesiastic was omitted, for the qualification was reduced simply to suitable men of good and tender conscience, even if they have not reached forty years of age but are more than thirty.[650] This became virtually the accepted formula, as shown in the commissions issued, June 4 and 5, 1507 by Julius II, to Enguera for Aragon and to Ximenes for Castile, and in those of Leo X to Mercader and Poul in 1513 and to Cardinal Adrian in 1516 and 1518.[651]