Scheiner wrote three of his books in Rome: "Rosa Ursina sive Sol" (Bracciano, 1626–1630), on sunspots, which served as a standard work for research work on the sunspots for a long time. "Rosa Ursina sive Sol" contains four books. In the first part, Scheiner discusses the question of priority of discovery in regard to sunspots. The second part not only describes telescopes, different kinds of projection and the helioscope but also compares the optics of the telescope to the physiological optics of the eye. In the third book, Scheiner presents a comprehensive collection of the data from his observation of sunspots. Book 4 consists of two parts: the first part deals once again with solar phenomena like sunspots and sun flares, the sun's rotation period of 27 days and the inclination of its axis of rotation. In the second part, Scheiner mentions numerous passages and quotations from the Bible, the writings of the Church Fathers and philosophers to prove that his geocentric view is in accordance with the teachings of the Catholic Church.