"Here Pharnaces... broke in... you are not going to draw me on... to answer your charges against the Stoics, unless we…"

"Reason may be employed in two ways to establish a point: firstly, for the purpose of furnishing sufficient proof of s…"

"[I]t does not follow that because heaven moves in a circle that the earth or something else rests at its center... be…"

"For it is now clear to me that there are no solid spheres in the heavens... But there really are not any spheres in t…"

"Now, so far as appearances go, it... the same thing whether the heavens, that is, all space with its contents, revolv…"

"The system of Anaxagoras, like that of Empedokles, aimed at reconciling the Eleatic doctrine that corporeal substance…"

"The language... as to the Moon's movements and the Epicyclic Theory... settled later on by Ptolemy... deserve careful…"

"When Copernicus, instead of leaving the earth at rest in the center of the world, gave it not only two rotations on i…"

"Rosen quotes various passages from De Revolutionibus in which Copernicus uses without distinction, the terms: princip…"

"Let us define the job of the astronomer in the classical phrase as "saving the appearances" of the celestial movement…"