The museums of medieval Europe, from Holland to Tuscany, are crammed with instruments and devices upon which the holy men labored devoutly, in order to see how long they could keep someone alive while being roasted. It is not needful to go into further details, but there were also religious books of instruction in this art, and guides for the detection of heresy by pain.
God is Not Great (ed. Atlantic Books Ltd, 2011) - ISBN: 9780857897152