Miguel Servetus was a 16th C Spanish physician and theologian (the two fields often went together at that time) who discovered the pulmonary circulation of the blood before William Harvey. He had a difference of opinion with John Calvin about the nature of the Trinity and Calvin had him burned alive, together with his books. Remember this when members of the major monotheistic sects give you lectures on the sanctity of life.

Servetus burning.jpg
Servetus stamp.jpg