CH. IX. COPERNICAN THEORY OF THE UNIVERSE. 65 



following the order of dates we shall be forced sometimes to 

 pass abruptly from one subject to another, it will, I think, be 

 the best way to teach you the * History ' of Modern Science. 



Copemican Theory of the Universe, 1474-1543. — It was 

 stated (p. 32) that about the year a.d. 100 Ptolemy formed a 

 * System of the Universe ' which supposed our little earth to 

 be the centre of all the heavenly bodies ; and the sun, toge- 

 ther with all the stars and planets, to move round us for our 

 use and enjoyment. This system had been held and taught 

 in all the schools for nearly fourteen hundred years, when, 

 in the beginning of the sixteenth century, a man arose who 

 set it aside, and proposed a better explanation of the move- 

 ments which we see in the heavens. 



In 1473, a ^^w years before Columbus sailed for America, 

 Nicolas Copernicus, the son of a small country surgeon, was 

 born at Thorn, in Poland. From his earliest boyhood he 

 had always a great love for science, and after taking a doc- 

 tor's degree at Cracow, he went as Professor of Mathematics 

 to Rome. About the year 1500 he returned to his own 

 country and was made a canon of Frauenberg, in Prussia. 

 Here he set himself to study the heavens from the window 

 of his garret, and often all night long from the steeple of 

 the cathedral. At the same time he read carefully the ex- 

 planations which Ptolemy and other astronomers had given 

 of the movements of the sun and planets. But none of 

 their theories satisfied him, for he could not make them 

 agree with what he himself observed ; until at last, after 

 twenty years of labour, he came to the conclusion that 

 the real explanation was the one which Aristarchus had 

 given (p. 20), and which was called the Pythagorean System^ 

 namely, that the sun stands still in the centre of our sys- 

 tem, and that the earth and other planets revolve round it 



