3. Although it gained rapid acceptance in the East, it was rejected by Pope John IV in 641. Its condemnation by the Sixth Ecumenical Council in 681 largely ended the controversy surrounding it, despite a brief revival attempt by Emperor Philippicus Bardenes in the early 8th century. It had been first proposed by the Emperor Heraclius in 638 as a compromise designed to end the raging monophysite controversy in the Eastern Church. For 10 points, name this Christian heresy which declared that Christ had two natures but a single will.