222 A SHORT HISTORY OF SCIENCE 



ing 'great and very wonderful spectacles, and offering them to the 

 consideration of every one, but especially of philosophers and as- 

 tronomers; which have been observed by Galileo Galilei ... by 

 the assistance of a perspective glass lately invented by him ; namely 

 in the face of the moon, in innumerable fixed stars in the Milky Way, 

 in nebulous stars, but especially in four planets which revolve around 

 Jupiter at different intervals and periods with a wonderful celerity; 

 which, hitherto not known to any one, the author has recently been 

 the first to detect, and has decreed to call the Medicean stars.' 



Whewcll. 



The reception which these discoveries met with from Kepler is 

 highly interesting, and characteristic of the genius of that great man. 

 He was one day sitting idle and thinking of Galileo, when his friend 

 Wachenfels stopped his carriage at his door to communicate to him 

 some intelligence. 'Such a fit of wonder,' says he, 'seized me at a 

 report which seemed to be so very absurd, and I was thrown into such 

 agitation at seeing an old dispute between us decided in this way, 

 that between his joy, my coloring, and the laughter of both, confounded 

 as we were by such a novelty, we were hardly capable, he of speaking, 

 or I of listening. On our parting, I immediately began to think how 

 there could be any addition to the number of the planets without 

 overturning my Cosmographic Mystery, according to which Euclid's 

 five regular solids do not allow more than six planets round the sun. . . 

 I am so far from disbelieving the existence of the four circumjovial 

 planets, that I long for a telescope, to anticipate you, if possible, in 

 discovering two round Mars, as the proportion seems to require, six 

 or eight round Saturn, and perhaps one each round Mercury and 

 Venus.' 



In a very different spirit did the Aristotelians receive the Sidereal 

 Messenger of Galileo. The principal professor of philosophy at 

 Padua resisted Galileo's repeated and urgent entreaties to look at 

 the moon and planets through his telescope ; and he even labored to 

 convince the Grand Duke that the satellites of Jupiter could not pos- 

 sibly exist. 1 



' There are seven windows given to animals in the domicile of the 

 head, through which the air is admitted to the tabernacle of the body, 



1 ' As I wished to show the satellites of Jupiter to the professors in Florence, they 

 would neither see them nor the telescope. These people believe there is no truth 

 to seek in nature, but only in the comparison of texts.' 



