JOHANN KEPLER 33 



farthest shore of Africa, bore up the sky on his shoulders, and Homer 

 placed the Aethiopeans at the extremities of the rising and setting sun, 

 thinking that because of the contiguity of the earth and sky there, the 

 sun was so close to them that it burned their skin. 



What form do they ascribe to the sky? The eyes ascribe to the 

 sky the shape of a tent, extending over our heads and beyond the sun, 

 moon and stars, or rather the shape of an arch overspanning the ter- 

 restrial plane, with a long curve, so that the part of the sky just over 

 the head of the spectator is much nearer to him than the part that 

 touches the mountains. 



What have men conceived in regard to the motion of the sky? 

 Whether the sky moves or stands still is not apparent to the sight 

 because the tenuity of its substance escapes the eyes, unless indeed 

 those things appear to stand still in which the eye can perceive no 

 variation. But the changing positions of the sun, moon and stars in 

 relation to the ends of the earth was apparent to the eyes. For the sun 

 seems to emerge from an opening between the sky and the immovable 

 mountains and ocean, as if coming out of a chamber, and having 

 traversed the vault of the sky seems to sink again in the opposite 

 region ; so also the moon, and the planets, and the whole host of stars 

 proceed as if strictly marshalled and drawn up in line, first one and 

 then the other marching along, each in his order and place. 



And so, since the ocean lies beyond the extreme lands, the mass 

 of men have thought that the sun plunges into the ocean and is extin- 

 guished, and from the opposite region a new sun issues forth daily 

 from the ocean. The poets have used this figure in their creations. 

 But, indeed, there have been even philosophers who have declared that 

 on the farthest shores of Lusitania could be heard the roar of the 

 ocean extinguishing the flames of the sun, as Strabo recounts. 



/ understand the forms of the sky and the earth and the atmosphere 

 surrounding the earth, also the place of the earth in the universe; now 

 I would ask what causes the stars to seem to rise daily from the one 

 part of the horizon and to sink in the opposite part; the motion of the 

 sky or of the earth? The astronomy of Copernicus shows that our 

 sight has led us astray in regard to this motion; for the stars do not 

 actually come up from beyond the mountains and climb toward the 

 zenith, but rather the mountains which surround us and which are a 



