KEPLER S LAWS. 307 



quite a modern science. It dates only from the sixteenth 

 century. 



Three great, three brilliant phases, have marked its 

 progress. 



In 1543 Copernicus overthrew with a firm and bold 

 hand, the greater part of the antique and venerable scaf 

 folding with which the illusions of the senses and the 

 pride of successive generations had filled the universe. 

 The earth ceased to be the centre, the pivot of the celes 

 tial movements ; it henceforward modestly ranged itself 

 among the planets ; its material importance, amid the 

 totality of the bodies of which our solar system is com 

 posed, found itself reduced almost to that of a grain of 

 sand. 



Twenty-eight years had elapsed from the day when 

 the Canon of Thorn expired while holding in his falter 

 ing hands the first copy of the work which was to diffuse 

 so bright and pure a flood of glory upon Poland, when 

 Wiirtemberg witnessed the birth of a man who was des 

 tined to achieve a revolution in science not less fertile in 

 consequences, and still more difficult of execution. This 

 man was Kepler. Endowed with two qualities which 

 seemed incompatible with each other, a volcanic imagina 

 tion, and a pertinacity of intellect which the most tedious 

 numerical calculations could not daunt, Kepler conjec 

 tured that the movements of the celestial bodies must be 

 connected together by simple laws, or, to use his own 

 expressions, by harmonic laws. These laws he under 

 took to discover. A thousand fruitless attempts, errors 

 of calculation inseparable from a colossal undertaking, 

 did not prevent him a single instant from advancing 

 resolutely towards the goal of which he imagined he had 

 obtained a glimpse. Twenty-two years were employed 



