102 SEVENTEENTH CENTURY. PT. in. 



Kepler. It will be instructive to notice here how very dif- 

 ferent these three astronomers, Tycho, Galileo, and Kepler 

 were, and yet how they each did their own part to add to 

 our knowledge. Tycho was a man who collected facts : his 

 work was dry, and his tables a mass of figures, such as most 

 people would think very uninteresting; yet if Tycho had not 

 spent his life in this dry conscientious work, Kepler could 

 never have discovered his laws. Galileo was a warm- 

 hearted enthusiastic observer : he loved the beauty of the 

 heavens, and knew how to make others love it too ; every 

 observation he made he told in popular language to the 

 world, and taught people the truth of the Copernican theory 

 by showing them plainly how they could prove it for them- 

 selves, if they chose to look at the heavens. Kepler was 

 quite different from either Tycho or Galileo ; he was a ma- 

 thematician, and worked everything out in his own brain by 

 accurate methods. He took Tycho's observations, which he 

 knew were true, and turned them this way and that way, 

 working out now one calculation, now another, and always 

 throwing them aside if they were not exactly true. He spent 

 years over his attempts, but it was worth while, for he 

 'arrived at three true laws, which will remain for ever. There 

 was only one point lie had not reached ; he knew that his 

 laws were true, but he did not know why they were true. 

 This was left for Newton to demonstrate nearly fifty years 

 afterwards. 



Chief Works consulted. Brewster's 'Martyrs of Science;' Herschel's 

 * Astronomy ; ' Denison's ' Astronomy without Mathematics ; ' Airy's 

 ' Popular Astronomy ; ' Drinkwater's ' Life of Kepler ; ' Baden 

 Powell's ' History of Natural Philosophy.' 



