Excerpts from Books and Wikipedia
Pope Sixtus IV (Francesco della Rovere) was personally involved in the Pazzi Conspiracy. He commissioned the construction of the Sistine Chapel. He authorized an Inquisition against converted Jewish Christians in Spain at the request of Catholic Monarchs. [Wikipedia] "Isabella of Castile and Ferdinand of Aragon--whose marriage in 1469 had brought together the two kingdoms of medieval Spain--saw it as their divine duty to drive heresy from their lands. . . . The crown, the Inquisition, and the informers all got a share of the victim's confiscated property. The Inquisition later moved on to target humanists and Protestants, especially during Philip II's reign. This was used as propaganda by Spain's enemies, particularly in England, and it was at this time that the Spanish Inquisition acquired its, possibly exaggerated, reputation for sadistic cruelty." [Furtado: 1001 Days] "The Spanish Inquisition was set up to cure the perceived ills created by five hundred years of a society that did tolerate contradictions of all sorts." {Menocal: Ornament of the World, p. 271]