216 A SHORT HISTORY OF SCIENCE 



sphere to the strength of those rays which fall on the larger 

 sphere." He explains the estimation of distance by binocular 

 vision. He supposes the velocity of light to be infinite. His 

 more purely mathematical work will be mentioned in a later 

 chapter. 



Kepler added Plato's boldness of fancy to his own patient and 

 candid habit of testing his fancies by a rigorous and laborious com- 

 parison with the phenomena ; and thus his discoveries led to those of 

 Newton. Whewell. 



If Kepler had burnt three-quarters of what he printed, we should 

 in all probability have formed a higher opinion of his intellectual 

 grasp and sobriety of judgment, but we should have lost to a great 

 extent the impression of extraordinary enthusiasm and industry, and 

 of almost unequalled intellectual honesty, which we now get from a 

 study of his works. Berry. 



Kepler says : ' If Christopher Columbus, if Magellan, if the 

 Portuguese, when they narrate their wanderings, are not only ex- 

 cused, but if we do not wish these passages omitted, and should lose 

 much pleasure if they were, let no one blame me for doing the same.' 

 Kepler's talents were a kindly and fertile soil, which he cultivated 

 with abundant toil and vigor, but with great scantiness of agricultural 

 skill and implements. Weeds and the grain throve and flourished 

 side by side almost undistinguished ; and he gave a peculiar appear- 

 ance to his harvest, by gathering and preserving the one class of plants 

 with as much care and diligence as the other. Whewell. 



Endowed with two qualities, which seemed incompatible with 

 each other, a volcanic imagination and a pertinacity of intellect which 

 the most tedious numerical calculations could not daunt, Kepler 

 conjectured that the movements of the celestial bodies must be con- 

 nected together by simple laws, or, to use his own expression, by 

 harmonic laws. These laws he undertook to discover. A thousand 

 fruitless attempts, errors of calculation inseparable from a colossal 

 undertaking, did not prevent him a single instant from advancing 

 resolutely toward the goal of which he imagined he had obtained a 

 glimpse. Twenty-two years were employed by him in this investiga- 

 tion, and still he was not weary of it ! What, in reality, are twenty- 

 two years of labor to him who is about to become the legislator of 

 worlds ; who shall inscribe his name in ineffaceable characters upon 



