How They Got Galileo

Italo Calvino, translated by James Marcus

Galileo: Heretic (Galileo Eretico)

by Pietro Redondi
Princeton University Press, 356 pp., $29.95 (this review of the Italian edition appeared in La Repubblica in September 1983).

A man on the beach at Capua observes the sunset, not for artistic or poetic inspiration but for a scientific purpose: he wants to measure the velocity of the sun. However, he doesn’t have measuring instruments of any kind: he has only a system for establishing certain units of time, of which long practice guarantees him constant accuracy: “As the sun disappeared on the horizon in a symphony of colors, he recited two Miserere, truly a very brief fraction of time.”

This man is the future cardinal and future saint Roberto Bellarmino, who had had in his youth a genuine scientific passion, as he recalled in an ascetic book of his old age; the seventeenth century impulse toward the natural sciences and mathematical exactitude had captured even the man who would become the strict restorer of Catholic doctrine at the Council of Trent. In 1616, he would summon Galileo (with, however, all the respect due to the admired man of science) so the Church could issue its first official injunction against the Copernican theory.

Bellarmino is one of the principal characters in Pietro Redondi’s book Galileo: Heretic. Another, indeed almost the leading, character is the Jesuit Orazio Grassi, who was the target (under the fictitious name of Lotario Sarsi) of Galileo’s sarcasm in his book The Assayer, and whose revenge (according to the thesis that Pietro Redondi proposes as highly probable) was the source of the Holy Office’s condemnation of Galileo in 1633.

As Redondi points out, on the specific question of comets, which gave rise to Galileo’s polemic in The Assayer, it was Grassi-Sarsi who was correct about the facts, not Galileo. Besides being an astronomer and mathematician, Grassi was also an architect, and he was entrusted with the project for the Church of St. Ignatius, the most important church of the Society of Jesus. Certainly, then, not a personage to make light of; indeed Galileo in Florence followed his movements through a network of his faithful friends in Rome. They even managed to describe to him Grassi’s reaction when the first copy of The Assayer had appeared on the counter in a Roman bookshop.

But with a reversal of roles that gives rise to one of the most delightful pages of Redondi’s historical inquiry, Father Grassi, who had a few tricks up his own sleeve, transformed himself from the spied-upon to the spy, making use of the same people who were watching him. A faithful follower of Galileo, Guiducci, who had the task of keeping an eye on the plots of the Roman Jesuits and passing them on to the master, was such a candid soul that he allowed himself to be taken in by Grassi’s professions of friendship, and let Grassi wheedle out of him information on the Dialogues Concerning Two New Sciences that Galileo was writing at the time.

What I’ve said so far should be sufficient to suggest that Redondi, a young historian of science, a …

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