"The Holy Spirit intended to teach us in the Bible how to go to heaven,
not how the heavens go."
Galileo Galilei
GALILEO GALILEI vs THE CHURCH:
INCOMPATIBILITY OF SCIENCE AND RELIGION
(1616 - 1642)
On February 17, 1600, the Catholic Church made a most emphatic and brutal statement.
Giordano Bruno, a Dominican friar, figure 1, turned philosopher, was burned at the stake in
Rome. In keeping with the punishment he suffered the heretic's fork, a cruel Y-shaped object,
the branched end of which passed into his jaw while the lower end was positioned behind his
breastbone to force his mouth shut. Bruno had been found guilty of heresy and the fork
meant that he could not longer "spread the word". His crime? Well, he was a sort of "hippie"
and among his rather "way out" views for the time, he believed and maintained the
Copernican model of the universe - that is the Earth not the Sun was at the center of the
universe - and also that the universe was infinite - with the possibility of multiple inhabited
worlds. Both views were heresy in the eyes of the Roman Catholic Church. The Catholic
Church itself was under considerable threat at the time through the Protestant Reformation
and what it feared most was "new" ideas. The current view of the Church at that time was
that God's Earth and God's children occupied a special place in the universe - they were at its
very center. The Church, then, provided the unspoken word of God and it spoke from Rome.
Giordano Bruno had spoken out against this dogma and for that crime he was investigated by
the Holy Inquisition in Rome. His interrogator, Robert Cardinal Bellarmine - we'll meet him
again later in the story - found the case against Bruno proved and so he suffered the ultimate
punishment. Today, in Rome, in the Campo dei Fiori - which translates as the Field of
Flowers - once the scene of public executions, you will find a statue of Giordano Bruno.
This is the backdrop of our story; the conflict between science and scientists, and the deeply
held views of the Church and Churchmen. In truth it was a conflict between fact and
dogmatic faith, a theme that is still with us today. An observation, if confirmed, becomes an
indisputable fact; faith, on the other hand, involves (and requires) the conscious desire to
believe in something. On the face of it, facts should always win out against beliefs, but
throughout history there are numerous examples where this has simply not been the case.
Today's story is just one of them. Some writers believe that the feud between Galileo and
Pope Urban VIII started the schism between science and religion. I'm not sure that's true several of Galileo's predecessors and contemporaries also experienced difficulties, real or
imagined, nor was persecution confined to Catholics; for example, Johannes Kepler, a
Protestant, and a contemporary of Galileo, was hounded by the Lutherans. But Galileo's case
is probably the best example and certainly the most well known.
Galileo held controversial views and he expressed them openly both verbally and in a number
of books. But what brought the feud to a head was his book, Dialogue on the Great World
Systems, The Ptolemaic and Copernican that was published in 1632, figure 2. The book
purported to compare - but not pass judgment on - the two contrasting ideas of the solar
system. The existing, and accepted system was that due to Claudius Ptolemy introduced in
the 2nd century AD although it had its roots in Aristotle's philosophy of the 4th century BC.
It was a very complicated system, figure 3, based solely on circles, which Aristotle considered
"perfection", with the Sun and planets circling the Earth, which was fixed and at the center.
The motions were extremely complicated but they gave, more or less, the right answer, in
terms of where a planet would be seen at a particular time from Earth. To the Greeks that
was much more important than understanding the actual mechanism itself.
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In contrast, the Copernican system, figure 4, which was proposed formally in 1543, is much
simpler. Why, asked Galileo, as had Copernicus before him, would God make something so
complicated when it could be made much simpler? All that was needed to explain the motion
within the solar system was a central Sun, with the other planets, including the Earth, which
also rotated on its own axis, going around it in circles! The Moon, also going around the Earth
in a circle, was carried along by the Earth. God and Heaven and the stars were all on the
outside.
Of course, there is a good deal of background as we'll see shortly, but in brief, in the book
Galileo suggested that the Earth rotated one every 24 hours on its own axis and that it circled
the Sun once a year in keeping with the Copernican system. It may not seem that
revolutionary to us today but, in reality, it changed everything! For no longer was Man and
the Earth the center of the Universe; our planet was just one among 5 others that circled the
Sun, no more nor no less important, no more nor no less significant. It is truly difficult for us
today to imagine just how much of a problem that was for people to accept. I suppose that
the nearest I could propose as a shock today would be for us to be contacted directly by extraterrestrial intelligent life. One can only imagine the sociological and psychological effects that
would have on the population on Earth to discover that we are not alone. Think about it; it
would necessarily involve a major transition in thought. So, when it was discovered that the
Earth was not the center of the universe, it was, in my view, the "greatest revolution" in the
history of Mankind to date.
In the 16th and 17th centuries there was the problem of rationalizing all of this with the
scriptures. Although there are no specific references in the scriptures and Biblical texts to
the position of Earth relative to the Sun or the other planets, according to the Church there
were enough "hints" that the Earth was not moving and so it had to be at the center. For
example, hadn't Joshua, at one time ordered the Sun to stop over Gibeon? And didn't it stand
still for a whole day? (Book of Joshua 10:12-13). Therefore, the clerics argued, the Sun must
be moving. Again, in the book of Ecclesiastes, it states (Ecclesiastes 1:5):
"The Sun also riseth and the Sun goeth down and hasteth to his place
where he arose";
doesn't that prove the Sun is moving? Also, common sense, they argued, told us the Earth
cannot be moving otherwise, wouldn't we be always in a howling gale and maybe get blown
away? And then again, if the Earth is moving, why does an object when it's thrown upwards
fall back into your hand and not fall behind you? In addition, the accepted geographical layout
had Hell in the bowels of the Earth - as evidenced by the fire and brimstone that spewed
occasionally from volcanoes - and the Sun, planets and stars circling the Earth on perfect
spheres, with God and Heaven beyond. So Copernicus's theory had to be wrong; not only did it
contradict the literal text of the Bible, it would upset the accepted geography! The Church
authorities dismissed the idea of the Sun being at the center of the universe, at least initially,
as a fad that would disappear, rather as we may regard some of the fashions and music of
young people today! But it didn't go away and towards the end of the 16th century it was very
risky to be a Copernican, as Giordano Bruno discovered.
In my view, history will record that there were three books that changed the world. The first
is De Revolutionibus by Nicolas Copernicus, published in 1543, in which Copernicus
suggested, albeit with no proof, that all the planets orbit the Sun. The second is the Dialogue
on the Great World Systems by Galileo, which provided the definitive proof. The third is the
Principia Mathematica by Isaac Newton, published in 1687, in which Newton explained the
details of the mechanics and the forces involved in the solar system. So, in the space of about
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140 years, the world was literally turned upside down and inside out! One can argue it was
Copernicus's De Revolutionibus that led to the war, and Newton's Principia that finished it,
but it was Galileo's Dialogue that won the war. Or, putting it another way,
"It's true the apple fell on Newton's head but it was Galileo who planted
the tree."
So, who was this man, Galileo? To most people, Galileo is probably best remembered for two
things; dropping objects like cannon balls from the top of the Leaning Tower of Pisa and the
invention of the telescope. Actually, neither of these notions are correct! If forced to describe
his contributions in a few sentences I would say he gave us not laws nor proofs, as Newton
did, but he showed us a coherence in the way things fit together to give the whole picture. He
combined common sense with mathematical logic, even if sometimes it flew in the face of
reason; for example, the fact that objects of different weight all fall at the same rate. That's
difficult to understand even today; you ask the students in my physics classes!
Galileo Galilei was born on February 15, 1564 in Pisa in Tuscany, on the east coast of Italy,
see figure 5. It was, incidentally, the very same day the artist Michelangelo died. His father,
Vincenzo Galilei, who was born around 1525 and died in 1591, was a well educated and
talented musician who published a book on musical theory in 1581. He had almost certainly
been a musician in the court in Florence, the capital of Tuscany, but for financial reasons he
was forced to move to nearby Pisa sometime before the birth of his eldest son Galileo where
he became a cloth merchant. Very little is known about Galileo's mother, Giula Ammannati.
Eventually, Galileo was to have two younger brothers and four sisters, see figure 6. One of his
brothers, Michelangelo, was shiftless and irresponsible and was to cause him considerable
anxiety in later life, principally because of unpaid debts.
The family remained in Pisa until Galileo was 10 years old and then they moved back to
Florence. Vincenzo remained ambitious for his first-born son hoping that the boy would
become a painter or musician. Indeed, he fostered these hopes by instructing Galileo in music
as well as drawing. After some schooling in Florence Galileo was sent to school at the
Camaldolese monastery of Vallombrosa, near Florence, where he was so attracted by the
quiet studious life that he entered the order as a novice. However, his father had other plans
and at age 17 years Galileo was enrolled at the University of Pisa as a medical student. As
far as his father was concerned, the medical profession was honorable and also had the
advantage of eventually producing an income.
But when Galileo reached university he found himself more intrigued by mechanics and
mathematics than his medical studies even though there was no serious department of
mathematics at the University at that time. He read the ancient texts of both Aristotle and
Plato, and those opposed to Aristotle, although the latter were little known and certainly not
favored by his professors. In class, any discussion of the laws of nature ended when an
appropriate quotation or opinion from Aristotle had been found. This was the method of both
instruction and proof - hardly the stuff to generate debate or expand knowledge! Galileo
dutifully memorized the texts but, regularly dissatisfied with the answers, he would react in
an outspoken way and would often question the validity of Aristotle's statements. His
behavior was unprecedented for the period and earned him the nickname "The Wrangler"
from both professors and fellow students. Even during his vacations he continued to study.
The story is that sometime told is that during the winter of 1582-83 Galileo was visiting the
palace of Francesco de Medici, the Grand Duke of Tuscany, when he passed a room where the
Medici children were being taught mathematics. The tutor, Ostilio Ricci, was explaining some
problem in geometry that fascinated Galileo. According to the legend he remained hidden
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hoping to hear more, ashamed of his ignorance. Shortly afterwards, he approached Ricci and
asked for some instruction, and Ricci gladly obliged. Apparently, Galileo grasped the
principles so quickly that he was soon able to study mathematics by himself.
Whether the story is true or not it was at this time that he discovered the works of
Archimedes and he became a devoted fan of his texts; in contrast to Aristotle, who had
believed everything could be explained by pure thought, argument and logic, therefore one did
not need experimental proof to check validity. Archimedes had been a theorist who used
experiments to prove or disprove his theories. Archimedes, then, was much more in the mold
of a "modern scientist".
It is believed that it was while Galileo was in his first year at the University of Pisa that he
discovered some of the principles of the pendulum. During prayers inside the Cathedral of
Pisa, it is claimed he watched a monk in the upper gallery draw the large chandelier towards
himself, light the candles and release it, figure 7. Apparently, Galileo noticed that when it first
started to swing, it moved swiftly through the darkness covering a large arc of swing. As the
length of the arc decreased the speed of the chandelier seemed less also. Using his pulse as a
timer he made the crucial discovery that the time of swing did not depend on the size of the
arc of swing. Back in his rooms he made and tested various pendulums and discovered the
principles of the simple pendulum, which are familiar to physics students of today.
One story that Vincenzo Viviani - who produced the first biography of Galileo some 10 years
after his death - tells us is that Galileo, being short of cash, tried to use his discoveries
concerning the pendulum to earn money. He still had some interest in medicine so he
developed a pendulum of variable - he said a doctor could adjust the length of string so that
the time of oscillation coincided with the patients pulse rate, therefore the patients heart beat
was given by the length of the pendulum.
On subsequent visits the doctor could monitor any changes in pulse-rate by simply comparing
the lengths of the synchronized pendulum! Apparently, the pulsilogium, as it was called, was
quite popular but it was so easy to copy he didn't earn much money! However, the story, like
many others associated with Galileo, is probably not completely accurate. It seems more
likely that the pulsilogium was introduced by Santori, later a professor of medical theory at
Padua, around 1600. He was a close friend of Galileo's and so it is quite likely they discussed
it. But it did lead to a new way of defining length in terms of time; quite a remarkable idea.
Galileo, himself, defined a pendule as the length of a pendulum that had a swing time of
precisely 1 second, see figure 8. It also lead to a new concept in time-pieces and sometime
later Galileo designed a pendulum clock with an escapement that allowed a toothed wheel to
advance one tooth at a time; the forerunner of the modern pendulum clock. However, the
first proper pendulum clock was actually constructed some years after Galileo's death by
Christiaan Huygens.
Galileo's father had worked hard to keep his son at University but after three years he had
reached the limit of his resources. So Galileo tried for a scholarship but since he had often
disputed Aristotle's ideas, his scholastic record was considered "poor" - as his answers were
rarely "correct". He was, in fact, as well trained as any scientist of his day and he had begun
to be recognized for his brilliance. However, because his academic record was considered
questionable, none of his instructors were inclined to support him. Therefore he left
University in 1585 without a degree and returned to the family home in Florence. He was
determined to become a physicist so he continued to learn mathematics and mechanics by
himself for the next 4 years. He did earn some money tutoring but he was seeking something
more permanent. His mathematical skills were becoming noticed and finally, but very
surprisingly, given his earlier history, he was given the Chair of Mathematics at the
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University of Pisa in 1589. It was a very poorly paid position since mathematics was
regarded of minor importance at Pisa. He gave his first lecture on November 12, 1589, aged
25 years. You can imagine the satisfaction he must have felt - he had become a University
Professor entirely on the strength of his own efforts, ability and dedication. Naturally, he had
to teach astronomy and this meant teaching the Ptolemaic, Earth-centered theory, based on
Aristotle's ideas. Obviously, had he not done so, he would have been out of a job! Altogether
he stayed at Pisa for three, remarkably productive years. It was there that he laid the
foundations for his quite revolutionary theories of motion, which were to occupy him for the
next 10-15 years. The details do not add much to our story today, except that many of his
theories and ideas were anti-Aristotelian and they were resented by may of the faculty at
Pisa. He had also upset quite a few people, including the Duke of Tuscany, because he would
often make tactless remarks; today, we would say that Galileo had poor people skills and he
did not suffer fools gladly. Also, he had some financial difficulties; since his father had died in
1591 he, as the eldest son had assumed responsibility for the family. He had to provide
dowries for his sisters Virginia and Livia and he was constantly bailing his young brother
Michelangelo and his family out of trouble. So he decided, after 3 years at Pisa, to leave and
seek his fortune elsewhere.
So, in 1592 he took the Chair of mathematics at the University of Padua, receiving
something like 3 times his salary at Pisa, where he stayed for 18 years. Padua, near Venice,
was one of the centers of the Renaissance and so the university was much more tolerant of
"new" ideas although Cesare Cremonini, the head of philosophy at the university, was a
strong advocate of Aristotle's every word. There was a very active intellectual community in
Padua itself and Galileo was very happy. It was there that he met Robert Cardinal
Bellarmine, who was to play an important role in Galileo's career as a scientist. The fact that
he had the respect of Bellarmine whose views, in truth, were sharply opposed to his own, says
much about his ability and personality, particularly if you remember we heard earlier that
Bellarmine was Giordano Bruno's Inquisitor and who sentenced him to death in 1600.
Galileo never married but lived for 10 years with Marina di Andrea Gamba, from about 1600
to 1610, and they had two daughters, Virginia (born in 1600) and Livia (born in 1601) and a
son, Vincenzo (born in 1606). None of the baptismal records list Galileo as the father; Virginia
is described rather brutally as "daughter by fornication of Marina of Venice" with no mention
of a father, on Livia's record the space was left blank and on Vincenzo's record it states
"father uncertain."
Galileo spent a good deal of his time in Padua perfecting his theories of motion and mechanics
but sometime in the early summer of 1609 he heard about a new invention in Holland, the
telescope. In fact, a patent had been sought for telescope, which consisted of two lenses in a
tube, by Hans Lippershey on October 2, 1608, see figure 9, albeit unsuccessfully. It seems
that Galileo did not believe the rumors at first but later in July 1609, he became convinced.
He had been seeking a salary increase at Padua and but had been told there was little hope.
Perhaps realizing the potential importance of a telescope to Venice as a maritime power he
built one of his own and around August 1609, he showed it to members of the court and
senate in Venice. Later, in a letter to his brother-in-law he said they were astonished when he
took them onto the top of the highest Bell Tower and had them look through his telescope;
they could see clearly ships approaching the harbor that were hardly visible to the naked eye!
Despite being offered life-tenure at Padua at nearly double his salary, the contract was very
confused and following a number of misunderstandings Galileo suddenly felt homesick for
Florence and in 1610 he decided to leave Venice.
So, Galileo did not invent the telescope, the person usually favored is Hans Lippershey, a lensgrinder who lived at Middleburg on the Dutch Island of Walscheren but the true origin of the
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telescope is not clear. Two Englishmen Robert Recorde (in 1551) and Leonard Digges (in
1571) refer to the use of 'perspectiveglasses' to view distant objects, and Digges even talked
about using mirrors. Also, William Bourne (in 1585) and Giambattista della Porta (in 1589)
claimed to have discovered a way to use two lenses to view distant objects. Actually, the idea
of using lenses as 'optical aids' can be traced back to the end of the 13th century when
Alexandro della Spina (d. 1313) and Salvino degl'Armati (d. 1317) invented spectacles
sometime between 1285 and 1300.
Lippershey was denied a patent because of the difficulties in establishing his priority for the
invention and because it was too easy to copy. However, he was asked by the Dutch
government to produce a 'two-eyed' version of the telescope - we now call them binoculars and in 1609 spy-glasses were actually on-sale in Paris! They gave upright images and were
intended for terrestrial use. Interestingly, there is a note in a brochure, dated November 22,
1608, that says that a telescope could also be used for
"seeing stars which are not ordinarily in view because of their
smallness".
Galileo was certainly not the first to use a telescope to look skyward; drawings of the Moon
exist that were made by Thomas Harriot in July 1609, possibly before Galileo had heard
about the telescope. But there is little doubt that Galileo's telescopes were certainly optically
superior. Altogether he is believed to have constructed some 100 telescopes during his
lifetime, the best was × 32, of which a few survive today.
Using his telescopes Galileo studied a variety of objects in the solar system beginning in the
winter of 1609-1610. Actually, he refers (in Latin) to his device as a 'perspicillum' often
translated as 'spyglass'; the word telescope was not coined until the year 1611.
•
In December 1609 he made detailed observations of the moon, see figure
10. He measured the heights of mountains from the shadows, and found some
were several miles high. It was, of course, this type of observation and
conclusion that set him head and shoulders above his contemporaries.
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Early in January 1610 he discovered 4 moons orbiting Jupiter, see figure
11. As I mentioned earlier, he was wanting to return to Tuscany and so in order
to re-ingratiate himself with the Medici family, who were the Grand Dukes of
Tuscany, he first called the group the Medicean planets and named the moons
after the Medici children. Although the Medici's were impressed, it was not well
received generally and shortly after they became known as the Galilean moons
and were re-named Io, Europa, Ganymede and Callisto.
Early in March 1610 Galileo published these discoveries in his Siderius Nuncius (Starry
Messenger) dedicated to Grand Duke Cosimo de' Medici of Tuscany. Not surprisingly, having
expressed a strong desire to return to Tuscany and having flattered the Duke, he was
appointed as chief mathematician and physicist to the Grand Duke with a non-teaching
appointment at the University of Pisa. He moved to Florence in September 1610 having sent
his daughters (then aged eight and ten years) there earlier to be with his mother and leaving
his son (aged four years) with Marina Gamba until he was old enough to leave her care.
Chief among his discoveries, published in Siderius Nuncius, were:
•
A 'rough' moon was entirely inconsistent with Aristotelian philosophy that
required all heavenly bodies to be pure, i.e, perfect spheres. Although he and his
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supporters did their best to convince clerics that the moon did indeed have
mountains, the contrary argument they put forward was that since the
mountains disappeared when the telescope was removed they must be an
artifact of the lenses!
•
Orbiting moons around Jupiter that contradicted the idea of natural
philosophers that the Earth was the center of all celestial motions.
•
He also determined that the Sun was not 'pure' - it was 'spotty' - and that
it took about 3-4 weeks to spin on its axis, see figure 12.
Soon after arriving in Florence, he also found that Venus was a planet, with phases like the
moon, proving conclusively that Venus revolved not around the Earth but around the Sun.
Almost everything he looked at seemed to contradict the earth-centered theory of Ptolemy
and the 'perfect' models of Aristotle but these discoveries had put him in serious danger and
he was beginning to get himself into very deep water with the Catholic Church. In fact, he
and his colleagues used to send coded messages and anagrams to each other to announce
their findings and to ensure that they would be properly credited later with their discoveries!
(Anagrams and coded messages were similarly used by both Newton and Huygens.)
Galileo's long period of service at Padua had brought him honor - the Department of Physics is
now named after him - as well as some controversy to the University. Grand Duke Cosimo
thought that Tuscany probably offered him a better 'political climate' for his studies.
However, the republic of Venice was a true republic. The Venetian Senate was sharply
opposed to any foreign intervention, even if cloaked in the sacred authority of the Church of
Rome. On the other hand the grand dukes of Tuscany remained subservient to the Church of
Rome. When he left Venice, then, in 1610, Galileo, aged 46, didn't realize he was leaving the
relative security of Venice and was putting himself in jeopardy in Tuscany; he truly believed
the most difficult times had passed. In reality, he was only making things easier for his
enemies.
The storm clouds were starting to gather around Galileo. Even some of his former colleagues
at Padua were denouncing his observations using the telescope. One of then, Cesare
Cremonini said:
"I believe that nobody but Galileo has seen them; and besides, looking
through those spectacles gives me a head-ache. Enough, I do not want to
know any more about it."
Some of the members of the Collegio Romano, the Jesuit educational headquarters in Rome
also had serious doubts. For example, Father Christopher Clavius, a every well-known
professor of mathematics thought that the discoveries were no more that faults in Galileo's
lenses! Others, like a certain Professor Giulo Libri, simply refused to look. When the
professor died Galileo suggested that although Libri would not take a look at celestial objects
while on Earth, perhaps he would take a view of them on his way to heaven! So Galileo felt it
would be good idea to visit Rome thinking that his observations with his telescopes and his
powers of persuasion would be enough to overcome all opposition not only on scientific
grounds but on religious ones too. He had the backing of the Grand Duke and he was on very
good terms with Cardinal Maffeo Barbarini - who we will meet again later - so he felt confident
he would not get much opposition from the Pope. He arrived in Rome in 1611 and his
reception was about as good as he had hoped. He was treated with great courtesy by the
Cardinals and he had long discussions with members of the Collegio Romano. There were
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some ominous signs, however. The influential Jesuit Cardinal Robert Bellarmine went to the
Collegio Romano, to ask them what they thought about Galileo's work but they gave him little
guidance. In fact, Bellarmine was in a real quandary. He had actually used a telescope and
was far too sensible to deny what he saw. But he was deeply concerned about the
consequences. After a short stay in Rome Galileo returned to Tuscany no doubt satisfied with
the result of his visit.
Shortly afterwards Galileo became involved in serious disputes with philosophers in Florence
about the veracity of mathematics and physics. These highly personal attacks by
philosophers became very serious and together with his Letters on Sunspots published in 1613,
in which he announces triumphantly his recent studies of Saturn, concluding that
"perhaps this planet also, no less than ... Venus, harmonizes admirably
with the great Copernican system ..."
placed him in increasing jeopardy. As a result, he became much more vulnerable to various
theologians for his 'anti-clerical' and 'heretical views'. In December 1614, for example,
Tomasso Caccini in Florence gave a vicious and highly critical sermon that denounced
mathematicians in general and the Galileists in particular, his text being the miracle of
Joshua, which I've already referred to. In truth, it was not clear that the Church of Rome
was entirely anti-Galileo because the early Church Fathers had recommended against any
linkage of Christian faith with matters that were irrelevant to salvation, and particularly if
time spent on studying them would interfere with time better spent in devout meditation.
Indeed, that had more or less been the separation urged by St. Augustine.
Around 1615, a letter written earlier by Galileo that hinted that the Bible need not be taken
too literally, fell into the hands of a Father Lorini. Lorini sent a copy to the Holy Office and
demanded that something be done about Galileo. Now, Cardinal Bellarmine was really on the
horns of a dilemma; on the one hand he was a Church bureaucrat, a defender of the faith and
one who wanted to accept the literal truth of the Bible; on the other hand, as an intellectual he
admired Galileo and had even made astronomical observations himself. Bellarmine
recommended that Galileo's views about a Sun-centered solar system be put to the so-called
theological qualifiers, a group of Dominican's who were like the guard dogs of Church dogma.
Their recommendations of censure were read at a weekly meeting of the Cardinals of the
Inquisition on February 24, 1616, and the Pope, Pope Paul V, asked Bellarmine to notify
Galileo in writing that he could:
"not hold nor defend"
Copernican theory. It should be pointed out, however, because of future ramifications, that it
the word 'teach' did not appear in the letter that Galileo was given. At the next meeting of the
Cardinals, Bellarmine reported that Galileo had been advised of the Pope's decisions and had
accepted it. Also, a decree was issued that placed on the Index of Prohibited Books all works
in which motion of the Earth and stability of the Sun were treated as real or unreconcilable
with the Bible. One such book was Copernicus's De Revolutionibus, where it was to remain
until 1835. (Surprising at that may sound, we should remember that Darwin's book on the
theory of evolution, which was published in 1859, was banned in some parts of the United
States until the 1960's.)
His visit to Rome had not been entirely disastrous, so Galileo returned to Florence and
continued his studies of Jupiter, to publish his observations and to contrast his methods and
scientific reasoning with
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"... the tiresome logical quibbles that seemed to satisfy philosophers."
As the file held in Rome against Galileo continued to grow it began to look as if he would need a
miracle to escape serious consequences. It seems as if he gets it, when in 1623, Pope Gregory
XV who had succeeded Pope Paul V, dies, and Maffeo Barbarini, a friend of Galileo, poet,
mystic and fellow Tuscan, was made Pope Urban VIII. Barbarini, a man never given to false
modesty, once claimed
"I know better than all the Cardinals put together; the word of a living
Pope is worth more than the sayings of a hundred dead ones."
Intermittently, from 1624 until around 1629 Galileo wrote his Dialogue, which compared the
Ptolemaic and Copernican systems. He felt he had little to fear from the new Pope, as he had
dedicated a number of his books to him, and during the writing of the Dialogue he had had a
total of 6 audiences with the Pope about the book. He was eventually given permission to
include his theory of the tides - which seemed to be the most controversial point - provided the
Earth's motion was portrayed as hypothetical since he had to satisfy the earlier edict of the
Inquisition. He had wanted to call the book Dialogue of the Tides but the censors made him
change it. After it was finished there were numerous delays due to some difficulties in getting
a license, first in Rome then in Florence so printing didn't start until June 1631. Eventually, it
went on sale in March 1632.
Galileo didn't want to simply 'state' his results as we do in publications today because he could
not have any ideas attributed directly to him as that would violate his agreement with Robert
Cardinal Bellarmine of 1616. Instead, he used a dialogue style in the form of conversations
between three persons, figure 2:
•
Salviati (probably modeled on Filippo Salviati (1582-1614)) - a
flamboyant, gregarious intellectual, in a sense a young Galileo,
•
Sagredo (probably modeled on Giovanni Francesco Sagredo (1571-1620))
- the 'opened minded' one, wealthy but bored with mundane ideas so he enjoyed
debate, and
•
Simplicio - the spokesman for all conventional ideas - whose arguments
were modeled after the philosophers who continually tried to discredit Galileo,
and therefore, held the Church's position.
The conversations took place at Sagredo's palace in Venice over a period of four days. They
had met to discuss the universe, with special reference to the problem of whether the Earth
travels around the Sun or whether it is a rest at the center of the universe. Galileo chose the
dialogue form for two reasons. Firstly, it was a particularly popular approach used to educate
the public, and secondly, as simply the "reporter", Galileo, could detach himself from
commitment to views that might be objectionable. The dialogue contained both the pro's and
con's of the two theories and was written in witty, zesty Italian - the 'popular' language of the
people - rather than Latin, the usual choice of scholars.
Naturally, poor Simplicio was hopelessly 'out-gunned' and 'outmaneuvered' by the logic and
the arguments of Salviati and Sagredo, and so on numerous occasions he had to agree with
them about the Copernican system. As we have seen, because he had good 'connections',
Galileo had managed to get the book through the censors, including the Pope Urban VIII, and
when it finally appeared in March 1632, it received a tremendous amount of publicity.
9
However, the full wrath of the Church descended on him almost immediately after it was
published and in August 1632 the Inquisition ordered all sales to stop. Although the book was
licensed, it was the final scene, a discussion of the tides, that was seen as the real problem.
There was no doubt that the Pope's argument that
"God can do things in any way he wants"
had been expressed by Simplicio, the simpleton. Putting the word of the Church in the mouth
of a simpleton was a serious political mistake. As a result, Galileo had not only offended the
Church but had insulted the Pope and that hurt Urban deeply.
There is little doubt that Galileo did it purposely but he did a poor job of concealing it. His aim
was to save the Church, to keep it "open" to new ideas and to have it work things out through
debate. He had always felt that the book of scripture and the book of nature shouldn't
contradict each other. But the Pope felt he had to defend the Church against friend or foe.
And the Church was facing a difficulty that still occurs today with those who hold literal
beliefs, the feeling that to give up a belief of one, single point is going to undermine the whole
thing. So the Church was unwilling to give up any of its beliefs in Aristotle and the Bible.
Accordingly, on September 23, 1632 Galileo, aged 68 years, was summoned to Rome to
appear before the Commissary General of the Holy Office, that is the interrogator on behalf
of the Inquisition. The Tuscan ambassador tried to intercede pointing out that Galileo was
not in good health but he only made things worse. The Pope explodes:
"Your Galileo has ventured to meddle in things he ought not and with
the most grave and dangerous subject that can be stirred up in these
days."
The Pope could not be assuaged, and Galileo was forced to journey to Rome and appear in
front of the interrogator, the Reverend Father Vincenzo Maculano.
The trial began on April 13, 1633, when Galileo was in his 70th year. Of course, this was no
ordinary trial; there was no council, the interrogator was both judge and jury, one was guilty
until proven innocent, it was held in secret and the interrogator, Father Maculano used the
third person.
However, although its operation was secret the Inquisition was meticulous about written
documents. The document produced by Galileo from Bellarmine, who incidentally had died in
1621, came as a complete shock to the Inquisitor. This is the memo signed by Bellarmine
that stated he, Galileo, should
"not hold nor defend ..."
Copernican ideas, which he felt he had managed to do in the Dialogue. After a short delay, the
interrogator produced a second memo dated February 26, 1616 that stated that Galileo
should:
"not hold nor defend nor teach in any way whatsoever, verbally or in
writing ..."
Copernican ideas. Not only was this memo not signed but it also carried no seal. Galileo knew
nothing of this document. But he now realized that since this evidence was produced on
behalf of the Church, he could never be acquitted without damaging the Church's authority
10
and reputation, and that can never happen. The interrogator offered Galileo a plea-bargain,
that if he admits some wrong-doing he would be treated leniently. Galileo was prepared to
acknowledge that in some places he may have gone too far perhaps, but he denied any
sinister intent. But the Pope was adamant, Galileo must face the full Inquisition.
Galileo knew full well what torture meant, but he was not tortured. He was sentenced to
recant his views under a charge of heresy and then placed under house arrest. Ten Cardinals
sat in judgment but oddly, only 7 signed the final decree; presumably, there must have been a
lack of unanimity among them. So, on June 22, 1633 he knelt before his Inquisitors in the
Great Hall of the convent of Santa Maria Sopra Minerva and recanted ...
"I, Galileo, son of the late Vincenzio Galileo of Florence, aged seventy,
arraigned personally before this tribunal and kneeling before you, most
Eminent and Reverend Lord Cardinals, general Inquisitors against
heretical depravity in the entire Christian dominion ... do swear that I
have always believed, and do now believe, and with God's help will in
the future believe all that is held and taught by the Holy Catholic and
Apostolic Church. But whereas, after an injunction which had been
lawfully intimated to me by this Holy Office that I must altogether
abandon the false opinion that the Sun is the center of the world and is
immovable, and that the Earth is not the center of the world and moves,
and that I must not hold, defend or teach in any way whatsoever, either
verbally or in writing, the said false doctrine, and after it had been
notified to me that the said doctrine is contrary to Holy Scripture, I
wrote and published a book in which I discussed this doctrine which
had already been condemned, and presented arguments in its favor
without offering any solution, I have been pronounced by the Holy
Office to be vehemently suspected of heresy ... Therefore, wishing to
remove from the minds of your Eminences and all faithful Christians
this vehement suspicion justly conceived against me, with sincere heart
and unfeigned faith I do abjure, curse and detest the said errors and
heresies and general each and every other error, heresy and sect which
is contrary to the Holy Church; and I swear that in the future I will
never again say or assert, verbally or in writing, anything which might
again give grounds for suspicion against me. ... I swear and promise also
to comply with and observe fully all the penalties that have been or may
be imposed upon me by this Holy Office. ... I, the said Galileo Galilei,
have abjured, sworn, promised and bound myself as above; and in
testimony of the truth I have signed the present document of my
abjuration with my own hand and recited it word for word in Rome, in
the Convent Sopra Minerva, this 22nd day of June 1633."
The Dialogue was added to the index of banned books where it remained until 1832. However,
copies had been smuggled out of Italy to other European cities where it was translated into
Latin and widely circulated among non-Italian scholars.
After several months of house arrest with Archbishop Piccolomini of Siena, he was allowed to
return to his own villa at Arcetri at the end of 1633 to live out the rest of his life in obscurity,
albeit under the eyes of officers of the Inquisition's officers. His daughter Virginia, now a nun
in a nearby convent, became chronically ill and in April 1634, about four months after his
return to Arcetri, she died. Her death was a tragic blow to Galileo; his other daughter Livia
and son Vincenzio were much less close to him, although Virginia had tried constantly to
mitigate the difficulties between Galileo and her brother.
11
During his imprisonment several books were published attacking the Dialogue but, of course,
he was not allowed to reply. He still worked with students and devoted himself to his final
great work, Discourses concerning Two New Sciences that dealt with his theories of fracture
and of motion, the book that many regard as his finest. It was completely anti-Aristotelian
and he used the same three characters and dialogue style as before. The manuscript was
completed in 1636 but because the Inquisition had banned all of his writings, it was taken to
Holland where it was published by Louis Elzevir in 1638.
Galileo's health was rapidly failing, he suffered bouts of asthma and he went blind in 1638 a
devastating blow for someone who had such a special talent for observation and had seen
further than others before him. Nearly helpless, he could only be visited by people who had
been 'approved' by the Holy Office although he was allowed to visit his son during part of 1638
so he could consult with doctors. At the end of 1638 the restrictions were relaxed a little and a
young scholar, Vincenzio Viviani, who later wrote the first biography of Galileo, moved into his
villa and in 1641 he was joined by Evangelista Torricelli (1608-1647), who became eminent in
his own right and is best remembered as the inventor of the barometer.
Galileo died on January 9, 1642, aged 77; the end of a truly remarkable life. He had been
crushed by the verdict of the Inquisition of
"... vehement suspicion of heresy..."
because it cut him off from the Church he apparently loved but he died with a clear
conscience. The Roman Church refused to relax its judgment of him and he was buried
without any great ceremony or memorial. In March 1737, the Church finally allowed Galileo
to be reburied in a grave with an elaborate monument in the church of Santa Croce in
Florence, see figure 13, which was built with the help of money left by Viviani expressly for
that purpose. Viviani's own remains were also moved to Galileo's grave as were those of
Galileo's daughter, Virginia. The year Galileo died, Isaac Newton was born. Whereas Galileo
had discovered how things moved, Newton would go on to discover why.
It is ironical to see how history works out. For instance, with a bit of luck Galileo might have
noticed another strange property while experimenting with his pendulums. For not only does
a pendulum swing back and forth in a plane, but it changes its direction of swing as the day
progresses. What is happening is the Earth is actually rotating under the pendulum! This
fact was not demonstrated until 1851 by the French scientist, Jean Foucault, and it gave the
first solid, physical proof that the Earth was rotating. It's certain that had Galileo noticed
this fact he would have shown it to Bellarmine and one can only speculate as to what effect it
would have had! Also, in 1997 the Galileo spacecraft found traces of chemicals that are
believed to be the very building blocks of life ... where did it locate it? ... on Europa, one of the
Moons of Jupiter discovered by Galileo in 1610.
Finally, was the document produced by the Inquisitor a forgery inserted later in Galileo's file or
was it a true record written by one of the Dominican's present at Galileo's meeting with
Bellarmine? The document has been studied and it certainly has no seal and no signature.
Also, it appears that it was written by two people; there are two different types of
handwriting. So, who knows? But, in the Fall 1980 Pope John Paul II ordered a new look at
the evidence against Galileo, and in 1992 a commission under Cardinal Paul Poupard found
Galileo Galilei had been "more perceptive" in his interpretation of the Bible than his
prosecutors. Moreover, the commission conceded that, as Galileo had suggested, the Bible
should be regarded as not always telling the literal truth, but sometimes as metaphor. The
Pope formally pardoned Galileo on October 31, 1992 almost 360 years after his trial ... better
12
late than never I suppose!
References:
The information found here is available from a variety of sources, including books and the
web. Specifically, I have used material from:
1.
2.
3.
4.
"Great Feuds in Science" by Hal Hellman (John Wiley and Sons - New York, 1998).
"Watchers of the Stars" by Patrick Moore (Michael Joseph Ltd. - 1973).
"Galileo" by Stillman Drake (Oxford University Press - 1980).
The Galileo Project web-site at: http://es.rice.edu/ES/humsoc/Galileo
13
Figure 1: Giordano Bruno (1548 - 1600)
14
Figure 2: Dialogue on the Great
World Systems, The Ptolemaic
and Copernican Published in
1632
15
Epicycle
Planet
Earth
Deferent
Figure 3: Motion of a planet around the Earth on
the Ptolemaic model (2nd century AD)
16
Figure 4: Motion of the planets around the Sun on
the Copernican model. De Revolutionibus (1543)
17
Venice
Padua
Pisa
Florence
Rome
Figure 5: Map of Italy at the time of Galileo Galilei
(born February 15, 1564 in Pisa).
18
Galileo
1564-1642
Benedetto
Virginia
1573-1623
Vincenzio Galilei
1520-1591
married 1562
Anna
Giulia Ammannati
1538-1620
Michelangelo
1575-1671
Livia
1578-
Lena (?)
Figure 6: Galileo Galilei’s family.
19
Figure 7: Chandelier in the Cathedral in Pisa.
20
l
A
B
Figure 8: A simple pendulum. If it takes 1 second to
swing from A
B
A then the length is one pendule
3
(24.8cm 9 inches)
4
21
Figure 9: Hans Lippershey’s patent application for the
telescope (October 2, 1608).
22
Figure 10: Two sketches of the Moon by Galileo
Galilei (Sidereus Nuncius, 1610).
23
Figure 11: Pages from Galileo’s notebook for January
7th to 14th, 1610 describing his discovery of four moons
of Jupiter.
24
Figure 12:
spots.
Galileo’s drawing of sun-
25
Figure 13: The author’s wife standing
by Galileo’s monument in Santa Croce,
Florence.
26