Studious Seclusion.—Waiting for the Correction of the Work of Copernicus.—Treatise on Tides.—Sends it to Archduke Leopold of Austria.—The Letter which accompanied it.—The three Comets of 1618.—Galileo’s Opinion of Comets.—Grassi’s Lecture on them.—Guiducci’s Treatise on them inspired by Galileo.—Grassi’s “Astronomical and Philosophical Scales.”—Galileo’s Reply.—Paul V.—His Death.—Death of Cosmo II.—Gregory XV.—“Il Saggiatore” finished.—Riccardi’s “Opinion” on it.—Death of Gregory XV.—Urban VIII. Seven years passed by, during which Galileo lived a secluded and studious life in the Villa Segni, at Bellosguardo, near Florence, without publishing any new work. How could he do so? The acceptance and further application of the Copernican system was the mainspring of all his scientific pursuits, of which, multifarious as they were, the principle of the double motion of the earth was both foundation and keystone. The general permission to employ the theory as a working hypothesis was of little service to him. The lofty structure of correct knowledge of our universe could not be raised on a pedestal of sand; it required the imperishable marble of truth. Galileo was compelled to withhold the results of his researches until, perchance, some altered state of things should change the mind of the papal court, at present so inimical to the Copernican cause. The publication of any researches in accordance with the Copernican system appeared especially dangerous, until the promised corrections had been made in the famous work of the Canon of Frauenburg, which had been temporarily placed on the Index. These corrections would give more[99] precise information as to how they wished the new doctrine handled at Rome, what limits had been set by ecclesiastical despotism to researches into nature. Galileo watched with great anxiety the labours of the papal censors, and tried to hasten them through his friend Prince Cesi.[159] This eager interest in the earliest possible publication of the corrections is another thing which does not accord with the assumed stringent prohibition of February 26th. What difference would it have made to Galileo whether any facilities were offered for the discussion of the Copernican theory or not, if absolute silence on the subject had been enjoined on him?
During this period, when he could not venture to have the results of his various researches published, he was careful to make them known to some friends of science by means of long letters, numerous copies of which were then circulated in Europe. Very few of them, unfortunately, have come down to us, but there is one of them that deserves special notice. It indicates precisely Galileo’s position: on the one hand he feels constrained to make way for the recognition of the truth; but on the other, as a good Catholic, and from regard to his personal safety, he does not wish to clash with ecclesiastical authority. This letter, too, adds weight to the conclusion that there was no prohibition enjoining absolute silence on the Copernican theory on Galileo.
During his last stay at Rome, at the suggestion of Cardinal Orsini, he had written a treatise on the tides in the form of a letter to that dignitary, dated January 8th,[160] in which he expressed his firm conviction, erroneously as we now know, that this phenomenon could only be explained on the theory of the double motion of the earth. He represented it as an important confirmation of the truth of it. In May, 1618, he sent a copy of this treatise to the Archduke Leopold of Austria, who was friendly to him, and was a brother of the Grand Duchess. But as since it was written the decree[100] of March 5th had been issued, which only permitted discussion of the subject as a hypothesis, Galileo thought it advisable to add a sort of accompaniment to his treatise, in which he took the utmost pains to comply with the conditions imposed by the Church on her dutiful and orthodox son. He wrote:—
“With this I send a treatise on the causes of the tides, which I wrote rather more than two years ago at the suggestion of his Eminence Cardinal Orsini, at Rome, at the time when the theologians were thinking of prohibiting Copernicus’s book and the doctrine enounced therein of the motion of the earth, which I then held to be true, until it pleased those gentlemen to prohibit the work, and to declare that opinion to be false and contrary to Scripture. Now, knowing as I do, that it behoves us to obey the decisions of the authorities, and to believe them, since they are guided by a higher insight than any to which my humble mind can of itself attain, I consider this treatise which I send you merely to be a poetical conceit, or a dream, and desire that your Highness may take it as such, inasmuch as it is based on the double motion of the earth, and indeed contains one of the arguments which I have adduced in confirmation of it. But even poets sometimes attach a value to one or other of their fantasies, and I likewise attach some value to this fancy of mine. Now, having written the treatise, and having shown it to the Cardinal above-mentioned, and a few others, I have also let a few exalted personages have copies, in order that in case any one not belonging to our Church should try to appropriate my curious fancy, as has happened to me with many of my discoveries, these personages, being above all suspicion, may be able to bear witness that it was I who first dreamed of this chimera. What I now send is but a fugitive performance; it was written in haste, and in the expectation that the work of Copernicus would not be condemned as erroneous eighty years after its publication. I had intended at my convenience, and in the quiet, to have gone more particularly into this subject, to have added more proofs, to have arranged the whole anew, and to have put it into a better form. But a voice from heaven has aroused me, and dissolved all my confused and tangled fantasies in mist. May therefore your Highness graciously accept it, ill arranged as it is. And if Divine love ever grants that I may be in a position to exert myself a little, your Highness may expect something more solid and real from me.”[161]
On reading such passages one really does not know which to be the most indignant at,—the iron rule by which a privileged caste repressed the progress of science in the[101] name of religion, or the servility of one of the greatest philosophers of all times in not scorning an unworthy subterfuge in order to disseminate a grain of supposed truth in the world without incurring personal danger.
But in spite of all precautions, in spite of “chimeras,” “fictions,” “fantasies,” and even “the voice from heaven,” the circulation of this treatise, based upon the theory of the double motion, would have been an infringement of the assumed absolute prohibition to Galileo, while, thanks to the ingenious accompaniment, it in no way clashed with the decree of 5th March. Galileo’s conduct shows plainly enough that he humbly submitted to the ecclesiastical ordinance, but there is not a trace of the prohibition to discuss the doctrine “in any way.”
Little, however, as Galileo desired to engage, thus hampered, in any perilous controversies, the next time it was nature herself who enticed him into the field in which his genius and his polemical ingenuity acquired for him both splendid triumphs and bitter foes.
In August, 1618, three comets appeared in the heavens, and the brilliant one in the constellation of the Scorpion strongly attracted the attention of astronomers. Although it was visible until January, 1619, Galileo had very little opportunity of observing it, as he was confined to his bed by a severe and tedious illness.[162] But he communicated his views on comets to several of his friends, and among others to the Archduke Leopold of Austria, who had come to see the sick philosopher.[163] He did not consider them to be real heavenly bodies, but merely atmospheric appearances, columns of vapour which rise from earth to the skies, to a very considerable height, far beyond the moon, and become temporarily visible to the inhabitants of the earth, in the well-known form of a comet, by the refraction of the sun’s rays. As he judged comets to be without substance, and placed them on a par with mock suns and the aurora borealis, he[102] concluded that they could have no parallax determinations.
In the same year, 1619, a Jesuit, Father Grassi, delivered a lecture on the three comets in the Roman College, in which he gave out that such phenomena were not mere appearances, but real heavenly bodies; copies of this lecture were widely circulated, and Galileo was strongly urged by his adherents to publish his opinion. He was prudent enough to evade for the time a fresh controversy, which, in the existing critical state of affairs, might bring him into danger, and apparently took no part in the scientific feud which was brewing. But he induced his learned friend and pupil, Mario Guiducci, consul of the Academy at Florence, to publish a treatise on comets. Numerous alterations and additions, however, which are found in the original MS. in the Palatina Library at Florence, attest that he had a direct share in the editorship.[164] The opinions hitherto held by philosophers and astronomers on this subject were discussed, and the author’s own—that is Galileo’s—expounded. Grassi’s views were sharply criticised, and he was reproachfully asked why he had passed over Galileo’s recent astronomical discoveries in silence.
Grassi, who recognised the re............