The precise moment at which Copernicus {620} formulated his theory in his own mind cannot be told with certainty, but it was certainly before 1516. He kept back his books for a long time, but his light was not placed under a bushel nevertheless. [Sidenote: 1520] The first rays of it shown forth in a tract by Celio Calcagnini of which only the title, "That the earth moves and the heaven is still," has survived. Some years later Copernicus wrote a short summary of his book, for private circulation only, entitled "A Short commentary on his hypotheses concerning the celestial movements." A fuller account of them was given by his friend and disciple, [Sidenote: Narratio prima, 1540] George Joachim, called Rheticus, who left Wittenberg, where he was teaching, to sit at the master's feet, and who published what was called The First Account.
Finally, Copernicus was persuaded to give his own work to the public. Foreseeing the opposition it was likely to call forth, he tried to forestall criticism by a dedication to the Pope Paul III. Friends at Nuremberg undertook to find a printer, and one of them, the Lutheran pastor Andrew Osiander, with the best intentions, did the great wrong of inserting an anonymous preface stating that the author did not advance his hypotheses as necessarily true, but merely as a means of facilitating astronomical calculations. At last the greatest work of the century, On the Revolutions of the Heavenly Spheres, [Sidenote: De revolutionibus orbium caelestium, 1543] came from the press; a copy was brought to the author on his death bed.
The first of the six books examines the previous authorities, the second proposes the new theory, the third discusses the precession of the equinoxes, the fourth proves that the moon circles the earth, the fifth and most important proves that the planets, including the earth, move around the sun, and gives correctly the time of the orbits of all the planets then known, from Mercury with eighty-eight days to Saturn with thirty {621} years. The sixth book is on the determination of latitude and longitude from the fixed stars. Copernicus's proofs and reasons are absolutely convincing and valid as far as they go. It remained for Galileo and Newton to give further explanations and some modifications in detail of the new theory.
[Sidenote: Reception of the Copernican theory]
When one remembers the enormous hubbub raised by Darwin's Origin of Species, the reception of Copernicus's no less revolutionary work seems singularly mild. The idea was too far in advance of the age, too great, too paradoxical, to be appreciated at once. Save for a few astronomers like Rheticus and Reinhold, hardly anyone accepted it at first. It would have been miraculous had they done so.
Among the first to take alarm were the Wittenberg theologians, to whose attention the new theory was forcibly brought by their colleague Rheticus. Luther alludes to the subject twice or thrice in his table talk, most clearly on June 4, 1539, when
mention was made of a certain new astronomer, who tried to prove that the earth moved and not the sky, sun and moon, just as, when one was carried along in a boat or wagon, it seemed to himself that he was still and that the trees and landscape moved. "So it goes now," said Luther, "whoever wishes to be clever must not let anything please him that others do, but must do something of his own. Thus he does who wishes to subvert the whole of astronomy: but I believe the Holy Scriptures, which say that Joshua commanded the sun, and not the earth, to stand still."
In his Elements of Physics, written probably in 1545, but not published until 1549, Melanchthon said:
The eyes bear witness that the sky revolves every
twenty-four hours. But some men now, either for love
of novelty, or to display their ingenuity, assert that the
earth moves. . . . But it is hurtful and dishonorable to
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assert such absurdities. . . . The Psalmist says that the
sun moves and the earth stands fast. . . . And the earth,
as the center of the universe, must needs be the
immovable point on which the circle turns.
Apparently, however, Melanchthon either came to adopt the new theory, or to regard it as possible, for he left this passage entirely out of the second edition of the same work. [Sidenote: 1550] Moreover his relations with Rheticus continued warm, and Rheinhold continued to teach the Copernican system at Wittenberg.