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The conventional wisdom or "Black Legend" has been discredited by modern historians.
The Real Inquisition --National Review
Despite popular myth, the Inquisition did not burn heretics. It was the secular authorities that held heresy to be a capital offense, not the Church. The simple fact is that the medieval Inquisition saved uncounted thousands of innocent (and even not-so-innocent) people who would otherwise have been roasted by secular lords or mob rule.Protestants promoted and perpetuated the "Black Legend" for obvious reasons.During the 13th century the Inquisition became much more formalized in its methods and practices. Highly trained Dominicans answerable to the Pope took over the institution, creating courts that represented the best legal practices in Europe.
As royal authority grew during the 14th century and beyond, control over the Inquisition slipped out of papal hands and into those of kings. Instead of one Inquisition there were now many. Despite the prospect of abuse, monarchs like those in Spain and France generally did their best to make certain that their inquisitions remained both efficient and merciful.
During the 16th century, when the witch craze swept Europe, it was those areas with the best-developed inquisitions that stopped the hysteria in its tracks. In Spain and Italy, trained inquisitors investigated charges of witches' sabbaths and baby roasting and found them to be baseless.
Elsewhere, particularly in Germany, secular or religious courts burned witches by the thousands. Compared to other medieval secular courts, the Inquisition was positively enlightened.