Florence and Rome

Again the gregarious and witty Galileo found intellectual companions among the
nobility. Most valued now was his friendship with the young, talented, and skeptical
Filippo Salviati. Galileo and his students were regular visitors at Salviati’s
beautiful villa fifteen miles from Florence. But even in this idyll Galileo was
restless. He had one more world to conquer: Rome—that is, the Church. In 1611,
Galileo proposed to the grand duke’s secretary of state an official visit to Rome
in which he would demonstrate his telescopes and impress the Vatican with the
importance of his astronomical discoveries.
This campaign had its perils. Among Galileo’s discoveries was disturbing evidence
against the Church’s doctrine that Earth was the center of the universe.
The Greek astronomer and mathematician Ptolemy had advocated this cosmology
in the second century, and it had long been Church dogma. Galileo could see in
his observations evidence that the motion of Jupiter’s moons centered on Jupiter,
and, more troubling, in the phases of Venus that the motion of that planet centered
on the Sun. In the sixteenth century, the Polish astronomer Nicolaus Copernicus
had proposed a cosmology that placed the Sun at the center of the
universe. By 1611, when he journeyed to Rome, Galileo had become largely converted to Copernicanism. Holy Scripture also regarded the Moon and the Sun as
quintessentially perfect bodies; Galileo’s telescope had revealed mountains and
valleys on the Moon and spots on the Sun.
But in 1611 the conflict between telescope and Church was temporarily submerged,
and Galileo’s stay was largely a success. He met with the autocratic Pope
Paul V and received his blessing and support. At that time and later, the intellectual
power behind the papal throne was Cardinal Robert Bellarmine. It was
his task to evaluate Galileo’s claims and promulgate an official position. He, in
turn, requested an opinion from the astronomers and mathematicians at the Jesuit
Collegio Romano, who reported doubts that the telescope really revealed mountains
on the Moon, but more importantly, trusted the telescope’s evidence for the
phases of Venus and the motion of Jupiter’s moons.
Galileo found a new aristocratic benefactor in Rome. He was Prince Frederico
Cesi, the founder and leader of the “Academy of Lynxes,” a secret society whose
members were “philosophers who are eager for real knowledge, and who will
give themselves to the study of nature, and especially to mathematics.” The members
were young, radical, and, true to the lynx metaphor, sharp-eyed and ruthless
in their treatment of enemies. Galileo was guest of honor at an extravagant banquet
put on by Cesi, and shortly thereafter was elected as one of the Lynxes.
Galileo gained many influential friends in Rome and Florence—and, inevitably,
a few dedicated enemies. Chief among those in Florence was Ludovico della
Colombe, who became the self-appointed leader of Galileo’s critics. Colombe
means “dove” in Italian. Galileo expressed his contempt by calling Colombe and
company the “Pigeon League.”
Late in 1611, Colombe, whose credentials were unimpressive, went on the
attack and challenged Galileo to an intellectual duel: a public debate on the
theory of floating bodies, especially ice. A formal challenge was delivered to
Galileo by a Pisan professor, and Galileo cheerfully responded, “Ever ready to
learn from anyone, I should take it as a favor to converse with this friend of yours
and reason about the subject.” The site of the debate was the Pitti Palace. In the
audience were two cardinals, Grand Duke Cosimo, and Grand Duchess Christine,
Cosimo’s mother. One of the cardinals was Maffeo Barberini, who would later
become Pope Urban VIII and play a major role in the final act of the Galileo
drama.
In the debate, Galileo took the view that ice and other solid bodies float because
they are lighter than the liquid in which they are immersed. Colombe held
to the Aristotelian position that a thin, flat piece of ice floats in liquid water
because of its peculiar shape. As usual, Galileo built his argument with demonstrations.
He won the audience, including Cardinal Barberini, when he showed
that pieces of ebony, even in very thin shapes, always sank in water, while a
block of ice remained on the surface.