words of his papal patron, Galileo ventured, soon after his return from Rome, to reply to a refutation of the Copernican system, which in 1616 had been addressed to him as its most distinguished advocate in the then favourite form of a public letter, by a certain Ingoli, then a lawyer at Ravenna, and afterwards secretary of the Propaganda at Rome. Ingoli, though an adherent of the old system, was at the same time a sincere admirer of Galileo, so that his arguments against the theory of the double motion of the earth were characterised by great objectivity. After the events of 1616, Galileo had wisely refrained from answering it; in 1618, however, it had been done by another corypheus of science, Kepler, in his "Extracts from the Astronomy of Copernicus,"[1] in which he valiantly combated Ingoli's objections. But the latter did not consider himself beaten, and replied in a letter addressed to a chamberlain of Paul V.
Now, after the lapse of eight years, Galileo thought that, protected by the favour of Urban VIII. he might venture on a reply to Ingoli. But he again took care in writing it not to come into collision with the decree of 5th March. With the assumed imperious prohibition of February, 1616, this step of Galileo's can be no more made to agree than his sending his treatise on the tides to the Archduke Leopold of Austria, 1618, or the publication of "Il Saggiatore." Galileo undertakes, in the reply to Ingoli, to defend the Copernican doctrine under a double pretext. On the one hand, he says he wishes to show that, as he had given currency to the new system of the universe before it was condemned by ecclesiastical authority, he had not been the defender of an improbable or unreasonable idea; on the other hand, he wishes to prove to the Protestant Copernicans in Germany, that in Catholic Italy the views of their great countryman had not been rejected from ignorance of their great probability, "but from reverence for Holy Scripture, as well as zeal for religion and
- ↑ This work was placed upon the Index of prohibited books by a decree of 10th March, 1619.
