AUTHOR’S PREFACE.

...the motions of the spheres of the world than those had proposed who profess Mathematics in the schools. And indeed, I first found in Cicero that Nicetus Likely Hicetas of Syracuse, a 4th-century BCE philosopher. had perceived that the Earth moves. Later, I also found in Plutarch that others were of the same opinion. I have decided to set down his words here, so that they may be available to everyone:

original: "οἱ μὲν ἄλλοι μένειν τὴν γῆν, Φιλόλαος δὲ Πυθαγόρειος κύκλῳ περιφέρεσθαι περὶ τὸ πῦρ κατὰ κύκλου λοξοῦ ὁμοιοτρόπως ἡλίῳ καὶ σελήνῃ. Ἡρακλείδης ὁ Ποντικὸς καὶ Ἔκφαντος ὁ Πυθαγόρειος κινοῦσι μὲν τὴν γῆν οὐ μήν γε μεταβατικῶς, τροχοῦ δίκην ἐνισμένοις ἀπὸ δυσμῶν ἐπὶ ἀνατολὰς, περὶ τὸ ἴδιον αὐτῆς κέντρον."

Others say that the Earth stands still, but Philolaus the Pythagorean says that it moves around the central fire The Pythagoreans believed in a "Central Fire" distinct from the Sun, around which all celestial bodies revolved. in an oblique circle, just like the Sun and the Moon. Heraclides of Pontus and Ecphantus the Pythagorean move the Earth, not through space, but like a wheel fixed on an axle, turning from west to east around its own center.

Taking this opportunity, I too began to think about the mobility of the Earth. And although the opinion seemed absurd, yet because I knew that others before me had been granted this liberty—to imagine whatever circles they pleased to demonstrate the phenomena Visible celestial events or appearances. of the stars—I thought it would be easily permitted for me as well to test whether, by assuming some motion of the Earth, more firm demonstrations than those of the others could be found in the revolution of the heavenly spheres.

And so, having assumed the motions which I attribute to the Earth later in this work, I finally found, through much and long observation, that if the motions of the rest of the wandering stars The planets. are compared to the Earth’s circulation and calculated for the revolution of each star, not only do their phenomena follow from this, but the orders and magnitudes of all the stars and spheres, and even heaven itself, are so interconnected that in no part of it can anything be moved without the confusion of the remaining parts and of the whole universe.

Accordingly, in the progress of the work, I have followed this order: in the first book, I describe all the positions of the spheres, together with the motions I attribute to the Earth, so that this book contains, as it were, the general constitution of the universe The physical layout and structural laws of the cosmos.. In the remaining books, I then compare the motions of the rest of the stars and all the spheres with the mobility of the Earth, so that it may be gathered from this to what extent the motions and appearances of the rest of the stars and spheres can be saved From the phrase "saving the appearances" (sozein ta phainomena); to provide a mathematical explanation that matches what we see. if they are compared to the Earth’s motions. Nor do I doubt that ingenious and learned Mathematicians will agree with me, if what...