314 EPOCHS IN THE HISTORY OF THE CONTEMPLATION 0* 



tions on the elliptic orbit of Mars ( 48 ) were began in 1601, 

 and gave occasion to the ' ' Astronomia nova seu Physica 

 ccelestis" completed eight years later. " By the study of the 

 orbit of the planet Mars/' writes Kepler, " we must arrive 

 at the knowledge of the mysteries of astronomy, or we must 

 Remain ever ignorant of them. By resolutely continued labour 

 I have succeeded in subjecting the inequalities of the motion 

 of Mars to a natural law." The generalization of the same 

 thought conducted Kepler to the great truths and cosmical 

 conjectures which he presented ten years later in his 

 Harmonices Mundi, libri quinque. " I believe/' he 

 writes, in a letter to the Danish astronomer Longomontanus, 

 "that astronomy and physics are so closely connected, that 

 neither can be perfected without the other." The results 

 of his investigations on the structure of the eye and the 

 theory of vision appeared in the " Paralipomena ad Vitel- 

 Konem," in 1604, and the " Dioptrica/' ( 481 ) in 1611. Thus 

 rapid, in regard both to the most important objects in the 

 phsenomena of the celestial spaces, and to the mode of ap- 

 prehending these objects through the invention of new 

 organs, was the extension of knowledge in the short interval 

 of the first ten or twelve years of the century, which opened 

 with Galileo and Kepler, and closed with Newton and 

 Leibnitz. 



The accidental discovery of the space-penetrating power 

 of the telescope was first made in Holland, probably as 

 early as the close of 1608. According to the latest do- 

 cumentary investigations, ( 482 ) this great invention may be 

 claimed by Hans Lippershey, a native of Wesel, and spec- 

 tacle-maker at Middelburg, Jacob Adriansz, also called 

 Metius, who is said to have made burning-glasses of ice," 



