What rendered this especially serious was the success of the Conversos in obtaining high office in Church and State. Important sees were occupied by bishops of Jewish blood; the chapters, the monastic orders and the curacies were full of them; they were prominent in the royal council and everywhere enjoyed positions of influence. The most powerful among them--the Santa Marías, the Dávilas and their following--had turned against the royal favorite Alvaro de Luna and, with the discontented nobles, were plotting his ruin, when he seems to have conceived the idea that, if he could introduce the Inquisition in Castile, he might find in it a weapon wherewith to subdue them. At least this is the only explanation of an application made to Nicholas V, in 1451, by Juan II, for a delegation of papal inquisitorial power for the chastisement of Judaizing Christians. The popes had too long vainly desired to introduce the Inquisition in Castile for Nicholas to neglect this opportunity. He promptly commissioned the Bishop of Osma, his vicar general, and the Scholasticus of Salamanca as inquisitors, either by themselves or through such delegates as they might appoint, to investigate and punish without appeal all such offenders, to deprive them of ecclesiastical dignities and benefices and of temporal possessions, to pronounce them incapable of holding such positions in future, to imprison and degrade them, and, if the offence required, to abandon them to the secular arm for burning. Full power was granted to perform any acts necessary or opportune to the discharge of these duties and, if resistance were offered, to invoke the aid of the secular power. All this was within the regular routine of the inquisitorial office, but there was one clause which showed that the object of the measure was the destruction of de Luna's enemies, the Converso bishops, for the commission empowered the appointees to proceed even against bishops--a faculty never before granted to inquisitors and subsequently, as we shall see, withheld when the new Inquisition was organized.[423] All this was the formal establishment of the Inquisition on Castilian soil and, if circumstances had permitted its development, it would not have been left for Isabella to introduce the institution. The Inquisition, however, rested on the secular power for its efficiency. In Spain, especially, there was little respect for the naked papal authority, while that of Juan II was too much enfeebled to enable him to establish so serious an innovation. The New Christians recognized that their safety depended on de Luna's downfall; the conspiracy against him won over the nerveless Juan II and, in 1453, he was hurriedly condemned and executed. Naturally the bull remained inoperative, and, some ten years later, Alonso de Espina feelingly complains "Some are heretics and Christian perverts, others are Jews, others Saracens, others devils. There is no one to investigate the errors of the heretics. The ravening