II 



NICOLAUS COPERNICUS 



1473-1543 



One of the first and most striking contributions to modern science 

 was the substitution of the Copernican for the Ptolemaic conception 

 of the universe. 



Nicolaus Copernicus was born in the Prussian village of Thorn, lo- 

 cated on the Vistula River, February ip, 14/3. Although destined 

 for the Church, he became interested in medicine, which he studied 

 at the University of Cracow. Later, he turned to mathematics and 

 continued his studies at the Universities of Vienna, Bologna, Padua, 

 Ferrara, and Rome. Although he settled doztm as canon at Frauen- 

 berg, Poland, and gratuitously practised medicine in conjunction with 

 his ecclesiastical duties, he found considerable time for other intel- 

 lectual pursuits. Reading widely in the Greek philosophers, he came 

 across a statement that the earth •moved in its own orbit. This 

 idea deeply appealed to him. ''Occasioned by this," he wrote, "I also 

 began to think of a motion of the earth, and although the idea seemed 

 absurd, still, as others before me had been permitted to assume cer- 

 tain circles in order to explain the motions of the stars, I believed it 

 would be readily permitted me to try whether on the assum^ption of 

 some motion of the earth better explanations of the revolutions of the 

 heavenly bodies might not be found. And thus I have, assuming the 

 motions zvhich I in the following work attribute to the earth, after 

 long and careful investigation, finally found that when the motions of 

 the other planets are referred to the circulation of the earth and are 

 computed for the revolution of each star, not only do the phenomena 

 necessarily follow there frotn, but the order and magnitude of the 

 stars and all their orbs and the heaven itself are so connected that in 

 no part can anything be transposed without confusion to the rest 

 and to the whole universe." 



In i^so he issue a ''Commentariolus" which outlined his theory, 



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