70 PART 1^ |^ EXPLORING THE SKY
that included the statement that Galileo was “not to hold,
teach, or defend in any way” the principles of Copernicus.
Some historians believe that this document, which was signed
neither by Galileo nor by Bellarmine nor by a legal secretary,
was a forgery. Others suspect it may be a draft that was never
used. It is quite possible that Galileo’s actual instructions were
much less restrictive; but, in any case, Bellarmine was dead and
could not testify at Galileo’s trial.
Th e Inquisition condemned Galileo not for heresy but for
disobeying the orders given him in 1616. On June 22, 1633, at
the age of 70, kneeling before the Inquisition, Galileo read a
recantation admitting his errors. Tradition has it that as he rose
he whispered “E pur si muove” (“Still it moves”), referring to
Earth.
Although he was sentenced to life imprisonment, he was,
perhaps through the intervention of the pope, confi ned at his
villa for the next ten years. He died there on January 8, 1642, 99
years after the death of Copernicus.
Galileo was not condemned for heresy, nor was the Inquisition
interested when he tried to defend Copernicanism. He was tried
and condemned on a charge you might call a technicality.
Nevertheless, in his recantation he was forced to abandon all
belief in heliocentrism. His trial has been held up as an example
of the suppression of free speech and free inquiry and as a famous
attempt to deny reality. Some of the world’s greatest authors,
including Bertolt Brecht, have written about Galileo’s trial. Th at
is why Pope John Paul II created a commission in 1979 to reex-
amine the case against Galileo.
To understand the trial, you must recognize that it was the
result of a confl ict between two ways of understanding the uni-
verse. Since the Middle Ages, biblical scholars had taught that
the only path to true understanding was through religious faith.
St. Augustine (ad 354–430) wrote “Credo ut intelligame,” which
can be translated as “Believe in order to understand.” Galileo and
other scientists of the Renaissance, however, used their own
observations as evidence to try to understand nature. When their
observations contradicted Scripture, they assumed that it was
their observations that truly represented reality. Galileo para-
phrased Cardinal Baronius in saying, “Th e Bible tells us how to
go to heaven, not how the heavens go.” Th e trial of Galileo was
not really about the place of Earth in the universe. It was not
about Copernicanism. It wasn’t even about the instructions
Galileo received in 1616. It was, in a larger sense, about the birth
of modern science as a rational way to understand the universe
(■ Figure 4-20).
Th e commission appointed by John Paul II in 1979, report-
ing its conclusions in October 1992, said of Galileo’s inquisitors,
“Th is subjective error of judgment, so clear to us today, led them
to a disciplinary measure from which Galileo ‘had much to suf-
fer.’” Galileo was not found innocent in 1992 so much as the
Inquisition was forgiven for having charged him in the fi rst
place.relevant to Copernicanism were banned in all Catholic lands,
although De Revolutionibus, recognized as an important and use-
ful book in astronomy, was only suspended pending revision.
Everyone who owned a copy of the book was required to cross
out certain statements and add handwritten corrections stating
that Earth’s motion and the central location of the sun were only
theories and not facts.
Dialogo and Trial
In 1621 Pope Paul V died, and his successor, Pope Gregory XV,
died in 1623. Th e next pope was Galileo’s friend Cardinal
Barberini, who took the name Urban VIII. Galileo rushed to
Rome hoping to have the prohibition of 1616 lifted; and,
although the new pope did not revoke the orders, he did
apparently encourage Galileo. Soon after returning home,
Galileo began to write his great defense of Copernicanism,
fi nally completing it at the end of 1629. After some delay, the
book was approved by both the local censor in Florence and
the head censor of the Vatican in Rome. It was printed in
February 1632.
Called Dialogo Sopra i Due Massimi del Mondo (Dialogue
Concerning the Two Chief World Systems), it confronts the ancient
astronomy of Aristotle and Ptolemy with the Copernican model
and with telescopic observations as evidence. Galileo wrote the
book in the form of a debate among three friends. Salviati, a
swift-tongued defender of Copernicus, dominates the book;
Sagredo is intelligent but largely uninformed. Simplicio, the
dismal defender of Ptolemy, makes all the old arguments and
sometimes doesn’t seem very bright.
Th e publication of Dialogo created a storm of controversy,
and it was sold out by August 1632, when the Inquisition
ordered sales stopped. Th e book was a clear defense of Copernicus,
and, probably unintentionally, Galileo exposed the pope’s author-
ity to ridicule. Urban VIII was fond of arguing that, as God was
omnipotent, He could construct the universe in any form while
making it appear to humans to have a diff erent form, and thus
its true nature could not be deduced by mere observation.
Galileo placed the pope’s argument in the mouth of Simplicio,
and Galileo’s enemies showed the passage to the pope as an
example of Galileo’s disrespect. Th e pope thereupon ordered
Galileo to face the Inquisition.
Galileo was interrogated by the Inquisition four times and
was threatened with torture. He must have thought often of
Giordano Bruno, a philospher, poet, and Dominican monk,
who was tried, condemned, and burned at the stake in Rome
in 1600. One of Bruno’s off enses had been Copernicanism.
However, Galileo’s trial did not center on his belief in
Copernicanism. Dialogo had been approved by two censors.
Rather, the trial centered on the instructions given Galileo in
- From his fi le in the Vatican, his accusers produced a
record of the meeting between Galileo and Cardinal Bellarmine