Nicolaus Copernicus gave the world perhaps the most important scientific insight of the modern age, the theory that the earth and the other planets revolve around the sun. He was also the first to proclaim that the earth rotates on its axis once every twenty-four hours. His theory was truly radical; during his lifetime nearly everyone believed that a perfectly still earth rested in the middle of the cosmos, where all the heavenly bodies revolved around it. One of the transcendent geniuses of the early Renaissance, Copernicus was also a flawed and conflicted person. A cleric who lived during the tumultuous years of the early Reformation, he may have been sympathetic to the teachings of the Lutherans. Although he had taken a vow of celibacy, he kept at least one mistress.