The first, however, whose work obtained any great notoriety, and who upheld the doctrine that the Earth revolved around the Sun, was Nicholas Kopernik, commonly called by the Latinised form of his name, Copernicus. He, too, was a German, born at Thorn, in 1473; he studied for a time at the University of Cracow, and like Nicholas de Cusa, afterwards in Italy, and was subsequently raised to the ecclesiastical dignity of a Canon. It is probable that he was not a priest (though he is frequently spoken of as such), but a Canon in minor orders. In 1500 he was appointed professor of mathematics at Rome; and such was his scientific reputation that he was consulted by the Council of Lateran, held in 1512, on the question of the reform of the calendar--a reform carried out at a later period by Pope Gregory XIII. The system of Copernicus was well received at Rome. A German disciple of his, John Albert Widmanstadt, in the year 1533, expounded it before Pope Clement VII., and produced a very favourable impression. Nor was the favour shown to Copernicus and his teaching ever withdrawn at Rome; his great work, “De Revolutionibus Orbium Cœlestium” (published, it is said, by the advice of Cardinal Schunberg, Bishop of Capua), was dedicated to the reigning Pope, Paul III.; nor does he appear to have received at any time the least rebuke or discouragement from the Holy See; he died, however, immediately after the printing of his book, in May, 1543. Copernicus supposed the heavenly bodies, the Earth included, to revolve round the Sun in _circles_; but, as it was evident that they did not exactly do this, he used the theory of epicycles, and supposed each planet to make two revolutions in each epicycle for every revolution round the Sun. The true solution of the difficulty was due to Kepler, who lived in the next century, and who discovered that the planets moved in _ellipses_. Copernicus held, and, of course, held truly, that the Earth revolves on its axis, thereby causing the apparent diurnal motion of all the heavenly bodies from east to west. Owing to his work having been the first of any great importance that maintained argumentatively the system called _heliocentric_, that is to say, in which the Sun is the real centre, round which the planets, including the Earth, revolve--for the treatise of Nicholas de Cusa does not appear to have had any extensive circulation--it is usual to speak of this system as the _Copernican_ one, notwithstanding the errors from which its great author was unable to extricate himself, and which have long since been rectified by subsequent writers; so that even at this day we retain the name.