sentences:  Then, in a lengthy introduction, Copernicus dedicated the book to Pope Paul III, explaining his ostensible motive in writing the book as relating to the inability of earlier astronomers to agree on an adequate theory of the planets, and noting that if his system increased the accuracy of astronomical predictions it would allow the Church to develop a more accurate calendar.At that time, a reform of the Julian Calendar was considered necessary and was one of the major reasons for the Church's interest in astronomy.The work itself is divided into six books