196 A SHORT HISTORY OF SCIENCE 



Copernicus was not a great observational astronomer. His 

 instruments were poor, his eyesight not keen, his location un- 

 favorable for clear skies. His recorded observations are few, 

 chiefly of eclipses or oppositions of planets, and of no high degree 

 of accuracy. His interest and genius lay rather in the direction 

 of profound analysis and careful mathematical revision of the 

 current geocentric theory, practically unchanged since its formu- 

 lation by Ptolemy thirteen centuries earlier. Unfortunately the 

 conditions of the time were adverse to the publication of so radical 

 an innovation as a heliocentric theory of the solar system ; nor 

 was Copernicus ever greatly interested in any publication of his 

 results, being both indifferent to reputation and averse to con- 

 troversy. 



' The scorn, ' he says, ' which I had to fear in consequence of the 

 novelty and seeming unreasonableness of my ideas, almost moved me 

 to lay the completed work aside.' 



Moreover, he realized the futility of publishing his revolu- 

 tionary theories until he should have buttressed them with a 

 planetary system so completely worked out that its superiority 

 to the long-intrenched Ptolemaic system should be unquestionable 

 a herculean, if congenial labor. Nevertheless, he gradually 

 formulated his astronomical system in manuscript, and about 

 1529 issued a Commentariolus giving an outline of his theory, 

 which thus became gradually but vaguely known to scholars. 

 Ten years later George Joachim Rheticus a young professor 

 of mathematics from the Lutheran university of Wittenberg, 

 visited Copernicus, eager to learn more of the new doctrine. 

 The Lutheran church was not more hospitable than the Roman 

 Catholic to scientific novelty and Luther himself called Copernicus 

 a fool. 



DE REVOLUTIONIBUS. In 1540 appeared the Prima Narratio 

 by Rheticus containing a considerable admixture of astrology, and 

 in 1543 the immortal De Revolutionibus Orbium Celestium, a copy 

 reaching Copernicus, it is said, on his death-bed. He begins with 

 certain postulates : first, that the universe is spherical ; second, that 



