THE SCIENTIFIC REVOLUTION - Catholic Textbook Project

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Introduction
The Scientific
Revolution
By the beginning of the 16th century, a new Europe was rising from the
epitome: a summary or
ashes of the Middle Ages.
embodiment
For all its problems and sins, the old medieval society had been cen-
tered on the Christian Faith as revealed through the teachings of the
Catholic Church. All of life found its meaning and purpose in attaining the life
that is to come—union with God, through Jesus Christ. Medieval men, of course, The Word of God as the great
did not neglect the good things of this life. They sought to create societies based on architect of the Universe.
Illumination from a 13th century
law and justice; they developed the practical arts of agriculture and manufacturing;
French Bible.
they cultivated the fine arts of architecture, painting, sculp-
ture, poetry, and music; and they sought to understand the
world around them through the study of philosophy. But for
the people of the Middle Ages, all these earthly goods were
seen to have one great purpose; they were to help lead men
and women to God. For medieval man, the Church and the
Faith were at the center of human life.
The Renaissance changed all this. Beginning in Italy in
the mid-14th century, scholars, poets, and artists discovered
a new interest in the classical civilizations of ancient Greece
and Rome. The ancient world became for them the model
of a perfect society; classical art, they thought, was the
epitome of true beauty. This new fascination with classical
civilization caused people to despise the Middle Ages as bar-
baric; they thought of it as just a “middle period” between
the glories of the ancient world and the rebirth (which
renaissance means) of classical culture in the 14th century.
First the Italian city of Florence, and then Rome herself,
became the center of the Renaissance and of humanism—
the belief that mankind’s goal in life is to attain the good
things of this earth.
Renaissance humanism was not necessarily contrary to
Christian culture, any more than reason is contrary to faith.
Many of the original humanists had been devout Catholics
who saw humanism as a way of enriching their religion, not
replacing it. Yet, humanism became increasingly atheistic—
not because humanists did not believe in God, but because
they more and more began to ignore him.
1
2 LIGHT TO THE NATIONS II: The Making of the Modern World
Interest in religion, however, did not die out in the Renaissance. Humanists were
among the chief critics of the corruption in the Church; they hoped for a renewal
of the true Christian faith in all its purity. It is not surprising, then, that many
humanists joined Martin Luther in his revolt against the Church, which began in
1517. Soon large sections of Germany, England and Scotland, Scandinavia, and even
many areas of France became Protestant. This Protestant Reformation or Revolution
destroyed the unity of Christendom and led to bitter wars of religion that shook
France and destroyed large sections of Germany. The Protestant Reformation, too,
ended the Renaissance.
A revolution, however, followed the Renaissance—the “scientific revolution.”
Though inspired by the ideas of certain ancient Greek thinkers, the scientific revolu-
tion did not seek to return to an earlier, more perfect age. It wanted to cast away the
philosophy and science of the Middle Ages—though it had received its basic way
of coming to know the world from medieval philosophers and men of science. The
scientific revolution was revolutionary because it created ways of thinking about
the natural world that were contrary to the ways people had been thinking about it.
This revolution was to change the world even more than the Renaissance did. It was the
first of many revolutions that ultimately gave birth to our modern world and changed
the face, not only of Christendom, but of every culture and civilization on Earth.
Philosophy and Science
Though today we think of science and philosophy as very different studies, people
in the 16th and 17th centuries did not. Then, the terms science and philosophy were
used interchangeably. Philosophers saw themselves as seekers after scientia (the Latin
word for knowledge), and the men we would today call scientists said their interest
was in “natural philosophy.” Furthermore, in the 16th and 17th centuries, the men
we would today call scientists also busied themselves in what we today would call
philosophy, and many a philosopher carried on studies in what we call science.
Black chalk sketch, by
Yet though they saw little or no difference between science and philosophy, the
Michelangelo, ca. 1560
people of the 16th and 17th centuries distinguished between different ways or meth-
ods of coming to know the world around them. As they saw it, there were two basic
paths of knowledge one could follow. One was the old path, blazed by the Greek phi-
losophers Plato and Aristotle and continued by the Scholastics of the Middle Ages.
The other path was also, in a sense, old—it came from the ancient Greek world, from
philosophers who had lived before Plato and Aristotle. But, as the 16th- and 17th-
century thinkers saw it, the path from that ancient Greek world to their own had
become overgrown and nearly lost over the centuries. These 16th- and 17th-century
thinkers saw it as their task to clear a new path through the “weeds” and “confusion”
of the Middle Ages, a path that would lead them more certainly to true knowledge
about the world.
The “Old Way”
One of the hallmarks of the Middle Ages had been western Europe’s rediscovery
of the works of the Greek philosopher, Aristotle. Many greeted the rediscovery of
Aristotle as a kind of renaissance in learning. Indeed, in the 13th century, Aristotle
was seen as a radical philosopher—so radical that some devout Catholics rejected
his works outright, for they saw his teachings as dangerous to the Catholic Faith.
It was the two great medieval thinkers, St. Albert the Great and St. Thomas
Aquinas, who demonstrated that, though some of Aristotle’s conclusions are con-
trary to the Catholic Faith, his way of doing philosophy is not. In fact, Aristotle’s
Introduction The Scientific Revolution 3
philosophy was seen to be the best way to understand the
world around us. Many thinkers thought Aristotle gave
theologians the best intellectual tools possible to explain
the mysteries of religion. Both Albert and Aquinas turned
Aristotle’s philosophy from being an enemy of the Faith to
become the handmaiden of theology.
But, over the centuries after the days of Albert and
Thomas, Aristotelian philosophy had become ossified.
Scholars did not question Aristotle—nor, for that matter,
did they question other ancient thinkers, such as the Roman
physician Galen and the Alexandrian astronomer, Ptolemy.
By the 16th century, many scholars thought that, to know
truth, all one had to do was read the works of these thinkers
—they thought, for instance, that what Aristotle said was
true because Aristotle said it. One did not need to find out
for himself whether what Aristotle and other ancient think-
ers said was true. One only had to accept it.
Such an attitude was contrary to what Aristotle him-
self had said was the true way to come to knowledge. For
Bust of Aristotle
Aristotle (as well as for Albert and Thomas Aquinas), all knowledge begins with
what we experience. The mind of every person begins as a “clean slate”—we are not
born with knowledge but come to knowledge as we grow older by understanding
the things we experience in the world. Through our senses of sight, hearing, and
touch, we come into contact with the world around us; and by thinking about the
things we sense, we are able to understand them, to have knowledge about them. We
do not learn primarily from books but by coming into contact with all the wonders
that surround us.
An example of how the “old way” of knowledge worked is the way people come
ossified: opposed to change,
to know about who and what we are. Human beings know themselves only by what
as if turned to bone (from
they experience about themselves and about other things. As a person grows, he the Latin word os, meaning
experiences other beings besides himself—not only his mother and father, family “bone”)
members, and other human beings, but beasts, plants, and such inanimate objects inanimate: without a soul
as rocks, water, and soil. Perhaps he first understands that the nonhuman creatures or life (from the Latin word
he sees, hears, tastes, and touches are in some ways very much like himself; but anima, meaning “soul” or
soon he begins to perceive that he is very different from them, as well. He sees, for “life”)
instance, that he is made of “stuff,” like they are, though often of a very different
kind of stuff. Then, he notices that he is more like plants and animals than rocks and
water, because, like plants and animals, he grows and develops. He then sees that
he is more like beasts than plants, because, like the beasts, he can move about from
place to place and has senses like they do. After a time, however, he learns that he
is quite unique from anything else in the world. Unlike all other creatures, he can
form ideas and think about those ideas.
All these experiences are the beginnings or “principles” of understanding and
knowledge. They are the beginnings of science. And these experiences encourage
the philosopher to give answers to the question, “What am I?” Understanding that
he has a body, five senses, and even emotions and passions, just like the beasts
have, the philosopher realizes that he himself is an animal. Then, seeing that,
unlike the beasts, he can think and reason, and even use his reason to make tools
for cultivating the soil or building the most marvelous machines, he understands
that he is more than just an animal. He comes to understand that he is a rational
animal, a being with a body, senses, and a mind that understands and makes con-
nections between things.
4 LIGHT TO THE NATIONS II: The Making of the Modern World
After answering the question, “What am I?” the philosopher makes other
query: a question or inquiry queries. His next question, perhaps, is “Why do I exist? What is the purpose for my
life?” Because he is different from other creatures, he comes to understand that his
purpose for existing must be different from that of all other creatures. He comes to
understand that because he can reason and know, and use his reason and knowl-
edge to make new things, his purpose in life is to understand the world around him
and be a maker and creator.
“Why do I exist?” however, is not the final question the philosopher asks. He does
not simply want to know what he is, or why he exists. He seeks to discover where he
comes from. In asking the question, “Where do I come from? Who made me?” the
medieval philosophers after much thought, gave the answer, God. It is God, they
said, who is the source from which they and all things come to be.
deduction: a method of rea- This method of reasoning is called deduction. It begins with principles that
soning where one begins with one discovers by thinking about his experience (and what others have said about
principles and, by asking ques- their own experiences); one then draws conclusions from those principles by ask-
tions, draws conclusions from ing questions.
those principles
To understand deduction, we have used the example of a philosopher coming to
principle: the first ideas in
know what a human being is. But medieval philosophers used deduction to under-
thinking, from which one
stand many other things as well, including mathematics, morality, politics, and
draws conclusions
who God is. By using deduction, of course, different philosophers came to different
conclusions on any number of questions; but, for centuries, nearly all philosophers
thought deduction was the chief and best way to understand the world, themselves,
and God.
The “New Way”
Though the best of medieval philosophers valued deduction as the means of com-
ing to the truth about the world, they insisted that all reasoning has to start with
German scholastic philosopher, experience. St. Thomas Aquinas, for instance, said that an argument based on
St. Albertus Magnus
authority (for instance, “this is true because Aristotle says it’s true”) is the weak-
(ca. 1193–1280)
est kind of argument in philosophy. Thomas, like other medieval
thinkers—like his teacher St. Albertus Magnus—insisted that all
proofs in philosophy had to be rooted in experimentum—the Latin
word meaning “experience.”
It was Albertus Magnus, however, who suggested another kind of
experimentum—the kind indicated by our English word, experiment.
What is an experiment? Firstly, it is a kind of experience, but a care-
fully controlled experience. It is a testing of a thing to see what it does
or how it behaves under very controlled circumstances. Experiment
can take the form of careful observation; for instance, a philosopher
or scientist may watch spiders to understand how they kill their prey.
He might choose several species of spiders to watch, and in observing
them, note down every detail he can discern of their movements. He
will then compare his observations, carried out over a period of time,
and come to some conclusions—for instance, that spiders inject a poi-
son into their prey to paralyze them before eating them.
A scientist may do more than merely observe natural things. While
observing them, he may actively test them. For example, in watching
ants move in single file along a path leading to and from their anthill,
the scientist wonders: What makes them infallibly follow this path? Is
it their sense of sight or smell, or something else? To discover this, he
may brush away the soil over which the ant path crosses. He notices
that the ants suddenly appear confused and wander about as if they
Introduction The Scientific Revolution 5
had lost their direction. From this trial, the scientist may conclude that it is the ants’
sense of smell, rather than their sight, that keeps them on their path.
The scientist or philosopher, however, does not simply accept his conclusion as
true. He continues to test his idea by more and more experiments. Other scientists,
too, may carry out similar experiments to test one scientist’s conclusions. If future
experiments do not give the same results, then scientists come up with new ideas to
describe what they have experienced. Only after many experiments give the same
results do scientists decide that their conclusions are really true.
Experiment is merely another kind of experience that we can use to understand
the world. But though it gives us much useful information, experiment alone can-
not tell us everything we need or want to know. Though experiment can show us,
for instance, how the human body is constructed or how it works, it cannot by itself
tell us about the human soul or the purpose for which human beings exist. We can-
not perceive these realities by the senses or measure them with our instruments. To
understand these realities, we need the “old way” of traditional philosophy.
The “new way, however, was really not as new as 16th century thinkers might
have thought it was. For one thing, it was rooted in the medieval Christian view of optics: the study of light, the
the world. Medieval Christian thinkers held that human reason could understand changes it undergoes and pro-
God’s creation because God had created patterns by which the universe and every- duces, and what is related to it
thing in it worked. Human reason could discover and understand these patterns. physics: the experimental sci-
ence that studies and measures
This conviction inspired Thomas Aquinas, but it also moved others to carry out the
the motion of bodies
experiments Albertus Magnus suggested. Like Albertus, the English bishop, Robert
heliocentric: Sun centered
Grosseteste (1168–1263), and others over the next two hundred years made careful
(from the Greek word helios,
observations of the world around them—observations that led to important discov-
meaning “sun”)
eries in astronomy, medicine, optics, and physics.
Yet, because philosophers had for so long neglected experiment as a means of
understanding the world around them, the thinkers who rediscovered experiment in
Detail of Nicolaus Copernicus
the 16th century thought they had happened upon something new. For these philoso- (1473–1543), monument by
pher-scientists, the way of experiment became the new way of “natural Fryderyk Tieck
philosophy.” And because what they came to discover through experi-
ments was so astounding and, sometimes, contrary to what everyone
had thought before, 16th-century thinkers began to reject the old way
of philosophy in favor of the “new way” of experimental science. They
began to think that experimental science was the only way to come to
a definite knowledge about the world.
The Copernican Revolution
Amid all the turmoil of religious revolt and war of 16th-century
Europe, one man lit a flame that would ignite all of Europe. This
man, a native of Poland, was Nicolaus (Nicholas) Copernicus.
Born in 1473, Copernicus later studied at the University of Krakow
in Poland and the University of Bologna in Italy. At Bologna he
became a member of the clergy, though not a priest, and studied
canon law and Greek. Though he would later add medicine and law
to his areas of study, Copernicus’s chief interest was astronomy. In
1500, he gave lectures on astronomy in Rome, and wherever he lived
he pursued careful observations of the stars and the planets.
Copernicus was the father of the heliocentric theory of the universe.
For centuries, all learned men had accepted the theory of the second-
century Alexandrian astronomer Ptolemy that the Earth sits at the
6 LIGHT TO THE NATIONS II: The Making of the Modern World
center of the universe and is the unmoving point around which the Sun, the plan-
ets, and the stars revolve in perfect circles. Ptolemy’s great work of astronomy, the
Almagest, explains the motions of the heavenly bodies by using complicated math-
ematics and giving ingenious explanations for why some heavenly bodies appear to
move more slowly during some parts of the year and more quickly during others.
geocentric: Earth centered Ptolemy’s geocentric theory, however, had problems. For one thing, his expla-
(from the Greek word Ge or nations for certain motions of the heavenly bodies were very complex. Following
Gaia, signifying the earth the lead of Aristarchus, an ancient Greek philosopher who held to the heliocentric
goddess) theory, Copernicus discovered that if he assumed that the Sun, not the Earth, is
the center of the universe, he could come up with simpler explanations for why the
heavenly bodies move as they do. For 25 years, Copernicus worked on his theory;
but when he had finally finished his great work, On the Revolution of the Heavenly
Spheres, he refused to have it published. His friends urged him to publish the work,
but Copernicus would not. He feared that those who did not understand it would
treat it with contempt.
Why was Copernicus so hesitant to publish his discoveries? It is perhaps hard for
us to understand—we, who think we know that the Earth moves around the Sun.
But in the 16th century and, indeed, for many centuries before, the idea that the
Sun, planets, and stars move around the Earth seemed obvious. After all, does it not
appear to us that the Sun moves around us, rather than that we move around the
Sun? To people of the 16th century, moreover, the theory that the Earth is the center
of the universe seemed to agree with Sacred Scripture, which in places speaks of
the Earth as stationary and the Sun as moving around it. Also, many 16th-century
people thought that, if man is God’s chief and greatest creature, is it not most fitting
that man’s home, the Earth, be the physical center of all creation?
For many people, Copernicus’s heliocentric theory was revolutionary. Ironically
it was the religious revolutionaries (men like Martin Luther and his associate, Philip
A “planisphere” showing the
Melancthon) who were Copernicus’s biggest opponents. The Protestant reformers
Copernican world system
thought the heliocentric theory clearly
contradicted Scripture. Copernicus,
however, received encouragement
from bishops and learned Catholics to
publish his work on the heliocentric
theory.
Though Copernicus understood the
controversy his heliocentric theory
would lead to in his own day, he
could not foresee the revolution it
would help create in the years to come.
Many would come to see Copernicus’s
ideas as a challenge to religion and
would use it as an example of how
science contradicts religion, and reli-
gion, science. So, though Copernicus
himself was a faithful Catholic, other,
less faithful thinkers would use his
heliocentric theory to justify rebellion
against the Catholic Church and all of
Europe’s past. It is for this reason that
Copernicus’s discovery of the heliocen-
tric theory has been called a revolution
—the “Copernican Revolution.”
Introduction The Scientific Revolution 7
Science and Christendom
Despite the interest shown in Copernicus’s heliocentric theory, astronomy and
natural science were not the major focuses of interest in the second half of the 16th
century. Religious controversies between Protestants and Catholics, reform of the
Church, how to protect Europe from Turkish invasion—these questions were of
greater importance to Europeans than whether the Earth moves around the Sun, or
the Sun around the Earth.
Interest in astronomy or in experimental science, however, did not die out in the
50 or so years after Copernicus’s death in 1543. Astronomy helped bring about an
important development—the reform of the calendar. Improved observations of the
stars and better knowledge of astronomy made it possible to draw up a new calen-
dar that better followed the course of the year. In 1582, a new calendar, called the
“Gregorian calendar,” instituted by Pope Gregory XIII, replaced the Julian calendar
that had been in use since the days of Julius Caesar.
The astronomy that brought about the Gregorian calendar, however, was not
based on Copernicus’s heliocentric theory. Most astronomers continued to explain
the universe using Ptolemy’s astronomy, and for one simple reason—Copernicus’s
theory had not been proven to be true. It was a hypothesis, just like Ptolemy’s theory.
A hypothesis is something like an educated guess, an idea presented as a way of
explaining what one experiences. A hypothesis becomes more certain only by being
more tested. Copernicus offered the heliocentric hypothesis as a way of explaining mechanics: a branch of physi-
the motions of stars and planets as people see them from the Earth. He thought his cal science that deals with
hypothesis was better than Ptolemy’s in explaining these motions, but not everyone physical forces and their effect
agreed with him. One of those who did not agree was a Jesuit, Christoph Clavius on bodies
(1538–1612), highly esteemed as both a mathematician and astronomer by the great-
est scholars of his time.
The Wonder of Florence
The city of Florence in Italy had long been an important center of
European culture. The home of Dante Alighieri (who wrote the
Divine Comedy) and of Leonardo da Vinci, Florence had become
famous for art and poetry. But another of Florence’s sons,
Galileo Galilei (1564–1642), would make it renowned for its
contributions to natural science.
Even as a young boy, Galileo had shown a remarkable
aptitude for mathematics and even mechanics—traits he
may have learned from his father, Vincenzo Galilei, who
had gained some fame as a musician and mathematician.
Yet, though a nobleman, Vincenzo was not wealthy, and he
wanted his son to learn a profession that would bring him
some wealth. But Galileo resisted his father’s pressure to
study medicine. Galileo’s interests were mathematics, mechan-
ics, and astronomy—and these interests he was determined to
pursue.
In 1589, at the age of 25, Galileo became professor of mathemat-
ics at the University of Pisa. It was there that he challenged Aristotle
himself and proved that in one area, at least, the great philosopher was
wrong. In his treatise, De Coelo (“On Heaven”), Aristotle seemed to say
that the larger a body of gold, lead, or any other material is, the faster it will
fall to the ground. Galileo proved this idea wrong by various experiments. Several Portrait of Galileo, by Justus
Sustermans
times, says one account, he dropped similar bodies of unequal size from the top
8 LIGHT TO THE NATIONS II: The Making of the Modern World
A Tale of Two Astronomers
Another of the “greatest scholars” who disagreed
with Copernicus was Tycho Brahe of Denmark.
Tycho, who was born three years after Copernicus died,
came from an aristocratic family. While studying at the
university in Copenhagen, Denmark, he discovered
Ptolemy’s Almagest. Forever after, astronomy became
the chief interest of Tycho’s life.
Having inherited a fortune from his uncle, Tycho
was able to transfer to the University of Wittenberg
in Germany to study mathematics and astronomy. To
escape a plague, he left Wittenberg for Rostock, and
there lost part of his nose in a duel. (No matter, Tycho
had a silver and gold nose made for him, and he wore it
for the rest of his life.) After traveling in Germany, Tycho
returned to Denmark where, in 1572, he discovered a
nova stella (a blast of light from the destruction of a
A planisphere showing Tycho Brahe’s world system
star) in the constellation Cassiopeia—a discovery that
made him famous throughout Europe.
Tycho’s fame helped him convince King Frederik II of
old astronomer died of a burst bladder in 1601, Kepler
Denmark and Norway to build him an observatory. The
inherited his instruments and the books in which Tycho
king gave him the island of Hveen (meaning “Venus”), off
had recorded his observations of the heavens. But Kepler
the coast of Denmark, and a good deal of money. Tycho
did not agree with Tycho’s rejection of Copernicus. Using
used the money to build a castle and gardens, complete
Copernicus’s heliocentric theory, Kepler studied the
with a library, observatories, and a workshop. There—and
movement of Mars and came to the conclusion that the
later in Prague, where he was employed by Emperor
planet did not move around the Sun in a perfect circle as
Rudolf II—Tycho carefully observed the stars, cataloguing
Copernicus said it did, but in an oval called an ellipse. But
them and marking them on a great globe of the heavens.
if this were true of Mars, why would it not be true of other
Tycho’s observations proved of great use to astrono-
planets? Kepler eventually concluded that all the planets
mers throughout Europe, but especially to the laboratory
move in elliptical paths around the Sun.
assistant who joined him in Prague in 1600. Johannes
Unlike a planet following a circular path (where it will
Kepler was born near Stuttgart, Germany, the son of an
always be equally distant from the Sun), a planet following
army officer who became a tavern keeper. Sent by the
an elliptical path will sometimes be closer to the Sun than
duke of Württemberg to study for the Lutheran ministry
at other times. In 1609, Kepler published a work showing
at the University of Tübingen in
that a planet will move more quickly along its elliptical
Germany, Kepler there learned
path when it approaches nearer the Sun. Kepler said this
of Copernicus’s theory and
was because the Sun acted like a giant magnet, attracting
became so enamored
the planet. By 1621, Kepler had compiled his findings in a
of astronomy that he
work he called the Epitome of the Copernican Astronomy.
decided to abandon
Kepler’s observations of the heavens led him to think
the ministry in order to
that the heavenly bodies always move according to certain
spend his time studying
patterns. These patterns, called “laws,” he said, are what
the stars.
govern the universe. Unlike later thinkers, however, Kepler
When Kepler arrived
did not think these laws replaced the providence of God.
in Prague, Tycho had
Kepler thought the order of the universe shows the power
not long to live. After the
and wisdom of God. A pious Protestant, Kepler wrote, “My
wish is that I may perceive the God whom I find every-
Johannes Kepler
(1571–1630) where in the external world in like manner within me.”
Introduction The Scientific Revolution 9
of the leaning tower of Pisa to demonstrate that the larger body did not fall more
quickly than the smaller one. Instead, both bodies fell at the same rate.
Both at Pisa and at the University of Padua, where he went to teach in 1592,
Galileo made important discoveries in mechanics and physics—the science that
studies and measures the motion of bodies. Among other important discoveries,
Galileo demonstrated that a body thrown or shot through the air always travels in
a parabolic curve. parabolic: having the shape
Even though Galileo’s most important discoveries were in physics, he is more or form of a curve called a
famous for his contributions to astronomy. In 1609, Galileo learned that an parabola
optician in the Netherlands had invented an instrument that allowed one to see optician: a grinder of lenses for
distant objects more closely. After a single night of thinking how this could be done, spectacles or glasses
Galileo designed an instrument that could make distant objects appear three times
larger than they appeared to the naked eye. Soon Galileo increased this power to 32
times and began using his invention, called the telescope, to look at the heavens.
In looking through his telescope, Galileo saw what no human being had ever
seen before. He discovered that the Pleiades constellation, which appears to the
naked eye as seven stars (the “Seven Sisters”), contains, instead, 36 stars. The Milky
Way, he found, is not just a swath of light across the night sky but is made up of
innumerable stars. Turning his telescope on the Moon, Galileo noticed that it was
covered with what appeared to be seas and mountains and valleys. But perhaps
more significant were his discoveries that the planet Jupiter had moons revolving
around it and that Venus and Mercury have phases like the Earth’s Moon does.
These last discoveries provided more evidence that Copernicus’s heliocentric theory
of the universe was true.
In defending and promoting Copernicus’s ideas, Galileo won undying popular
fame; however, his zeal for the heliocentric theory brought him into conflict with
the Catholic Church. This conflict gave Galileo the reputation as a “martyr for sci-
ence” and has made the Church appear to be an enemy of scientific research, learn-
ing, and all progress. It is to this conflict we now turn our story.
“But It Does Move!”
At times Galileo seemed quite a humble man. For instance, he wrote, “I have never
met a man so ignorant that I could not learn something from him.” Yet, despite such
statements, Galileo was proud and could be quite harsh with those who disagreed
with him. Firmly convinced that his discoveries had proven that the Copernican
heliocentric hypothesis was true, Galileo showed little patience with those who
A reconstruction of Galileo’s
telescope, with the cathedral of
Florence in the background
10 LIGHT TO THE NATIONS II: The Making of the Modern World
thought otherwise. For instance, writing in the margin of a book written to defend
the Ptolemaic system, Galileo called the book’s author (the Jesuit Antonio Rocco)
an “ignoramus, elephant, fool, dunce.”
But though he had little respect for Rocco, Galileo was on good terms with
other Jesuits—at least for a time. Jesuits had been among the foremost scientists
of Galileo’s day. The Jesuits in Rome were quite interested in Galileo’s discoveries.
In 1611, they welcomed him to Rome and allowed him to stay in their house in the
city. What’s more, Church prelates and Pope Paul V himself showed the astronomer
every sign of favor.
What then happened to sour Galileo’s friendship with the Church? As we have
seen, it was churchmen who urged Copernicus to publish his work, and churchmen
(particularly the Jesuits) who were eager students of natural science and had made
important scientific discoveries themselves. (For instance, the Jesuit Christoph
Scheiner of Ingolstadt had discovered sunspots in 1611, about the same time Galileo
himself did.) Why, then, did churchmen, and the Jesuits in particular, become
Galileo’s opponents?
The reason is that Galileo and the churchmen differed in how they understood
the importance of Copernicus’s ideas. Even the most scientific Jesuits thought
Copernicus’s heliocentric idea was a hypothesis, and only a hypothesis. That is,
they thought the heliocentric idea might be a useful instrument to help astronomers
describe the universe and make predictions about when solar eclipses and other
phenomena would occur. The Copernican hypothesis was a good tool, they thought,
but it did not necessarily describe the universe as it truly is.
Churchmen—and, indeed, many of the most learned men of Europe—
continued to hold to the notion that the Earth does not move and is the center of
the universe. They thought the idea that the Earth moves and the Sun is stationary
contradicted common sense. More important, they thought it contradicted Sacred
Scripture, which in some places seems to say very clearly that the Earth does not
move. Finally, in Galileo’s day, Copernicus’s hypothesis had not been thoroughly
proven. There were still good reasons to think it might be a false way of describing
the universe.
Galileo before the Holy Office,
Galileo thought differently. He was convinced that his discoveries proved that
1633. Oil on canvas by Tony
Robert-Fleury. Copernicus’s hypothesis was true, and he would not rest until he convinced every-