Discussion 6

Lecture 11: The Scientific

Revolution, 1600-1642

I do not feel obliged to believe that that same God

who has endowed us with senses, reason, and

intellect has intended to forgo their use and by

some other means to give us knowledge which we

can obtain by them.

---Galileo, Letter to Grand Duchess Christina (1615)

In a previous lecture I suggested that before Isaac

Newton could conceive of and demonstrate the laws of

universal gravitation, a practical understanding of

motion was required (see Lecture 10). This practical

understanding of mechanics would be provided by an

Italian astronomer and mathematician by the name of

GALILEO GALILEI. Born at Pisa in 1564, Galileo studied

medicine and mathematics and became a professor at

Pisa in the late 1580s. But because the largely

Aristotelian faculty was hostile to him, Galileo decided

to move on to Florence. Eventually he settled at Padua

and between 1592 and 1610 his mathematics lectures

at the university attracted students from across the

Continent.

The key to all of Galileo's discoveries was the accurate

measurement of time. Accurate

measurement of time was essential

if the mechanics of motion were to

be explained. By 1600, there were

no accurate clocks or time keeping

devices. There were clocks, of

course, but none of them were at all

precise. Medieval clocks were

convenient for dividing the day but

not for keeping precise time. Galileo

was fascinated with time. As the

story goes, Galileo was attending a

religious service at Pisa in 1583. His thoughts began to

wander and as he gazed about he noticed the swinging

motion of a lamp that hung from the ceiling. It was then

that Galileo was struck by the uniform motion of the

pendulum. The pendulum, if kept swinging at a constant

rate, keeps near perfect time. Galileo experimented

with various sorts of motions and falling bodies. This,

after all, was what helped him determine the mechanics

of motion. His observations of falling bodies at Pisa are

only the most well known of his experiments. He rolled

balls of varying size and weight down slopes with

varying angles of incline. He showed that an object

thrown into the air falls to the earth along a parabola.

What he ended up doing was casting doubt on

Aristotelian mechanics -- he challenged the monopoly

on scientific education enjoyed by university clerics who

had, so he thought, learned nothing since their earliest

encounter with Aristotle.

Around 1609 Galileo had news of a development from

Holland -- a lens grinder had taken two lenses and

placed them at opposite ends of a metal tube. A

rudimentary telescope was the result. Galileo made his

own telescope as well as a compound microscope.

Galileo directed all of his attention to the heavens. He

was the first man to see craters on the moon, sun spots

and the rings of Saturn. He also observed the phases of

Venus. He determined that the Earth's moon was not a

source of light but rather of reflected light. He saw the

moons of Jupiter. And of course, Galileo was also a

Copernican: "Sol est centrum mundi, est omnio

immobile motu locali," ("The sun is the center of the

universe and the earth moves.")

In 1611, Galileo packed his brass telescope in his bag

and decided to go to Rome. The previous year, Galileo

had reported his findings in his book, THE STARRY

MESSENGER. Criticism of Galileo's observations began

immediately. The authorities at Rome would not even

look through his telescope. Why not? They had absolute

faith in Aristotle. Not only that, if you think about it, the

telescope reveals the existence of things which are not

really there. Look at the heavenly body called Saturn

with the naked eye. Do you see its rings? Of course not.

In Galileo's day, seeing something that could not be

seen with the naked eye was the same thing seeing

apparitions or hearing voices -- it was the work of the

Devil! The religious authorities at Rome were uneasy

with the New Science. Copernicus, Kepler and Galileo

seemed to be turning the world upside down. The sun

was the center of the cosmos, the earth moved and the

sky seemed to hold hidden visions. In effect, the

Scientific Revolution had created an invisible world

behind the visible world and those men of an older

generation, weaned on Aristotle and Aquinas were

fearful of it.

On April 12, 1615, Cardinal Bellarmine (1542-1621)

wrote his famous LETTER TO FOSCARINI, a letter which

expressed his displeasure with Copernican theory. The

following year, Galileo was summoned to Rome and

ordered to desist teaching Copernican theory. He was,

however, free to think about Copernican theory, but he

could not teach it or write about it. Galileo agreed to

this condition but still maintained that his mechanical

philosophy described the natural world better than any

alternative explanation. He was confident, extremely

confident, that his position was the correct one. So

confident was Galileo that in 1632 he imagined that the

decree regarding his public advocacy of Copernican

theory could be overturned. He began to criticize the

clergy,

who would preach the damnability and heresy of

the new doctrine from their very pulpits with

unwanted confidence, thus doing impious and

inconsiderate injury not only to that doctrine and its

followers but to all mathematics and

mathematicians in general.

The new science, so though Galileo correctly, was

unsuited to pulpit discussion. In fact, Galileo was more

than aware of this necessity and in the defense of the

new science, we can see the first stage of a century

long struggle between faith and reason.

The new science was also unfit for public discussion. On

the one hand, as a practical man with an eye toward

the applicability of science, Galileo knew that the new

science could improve the human condition. On the

other hand, however, he argued that it was necessary

not to allow the public too much knowledge regarding

the motions of the heavenly bodies -- at the very least,

the public mind ought to be enlightened slowly and

cautiously:

The shallow minds of the common people must be

protected from the truth about the universe lest

they should become confused and obstinate in

yielding assent to the principle articles that are

absolutely matters of faith.

In Galileo's mind, the new science was a body of

knowledge intended for the learned elite. It was not

intended for public consumption.

Furthermore, Galileo argued, the new science did not

contradict the deeper meanings of the Holy Scriptures.

The wise man should seek the true sense of the

Scriptures, the true meaning. But, in matters of physical

problems, we ought not begin from the authority of

Scriptural passages but from sense experience and

necessary demonstrations: in a word, natural

philosophy. Aristotle had not observed enough, nor as

freely as Church authorities believed and so Galileo and

the rest of his fellow revolutionaries went beyond The

Philosopher -- they had done a much better job of using

their senses. By arguing that man must look beyond the

literal meaning of the Scriptures, Galileo unwisely put

himself in disagreement with Council of Trent. In 1546,

the Council prohibited "any attempt to twist the sense

of Holy Scripture against the meaning which has been

and is being held by our Holy Mother Church." The

Council, of course, was clearly reacting to the onslaught

of the Lutheran Reformation. The medieval synthesis

had been assaulted on several fronts but in one last

ditch effort, Rome built its last defense -- Galileo was

the fall guy!

In 1623, Galileo's friend and admirer Maffeo Barberini

was elected Pope Urban VIII (1568-1644). An intelligent

but vain man, Barberini had much in common with

Galileo -- both men considered themselves above the

common man. Galileo enjoyed six audiences with

Baberini and was rewarded with lavish gifts from him.

Galileo reasoned that the time was now right to publish

a new defense of Copernican theory. His confidence at

an all time high, he spent four years composing the new

Copernican manifesto. His Dialogue Concerning the Two

Chief World Systems, Ptolemaic and Copernican, was

cleared by Church censors, one of whom was Galileo's

former student, and was published at Florence in 1632.

As the title suggests, Galileo grounded his manifesto in

the form of a dialogue rather than a treatise. The

dialogue, Galileo reasoned, was a device through which

an argument for Copernican theory could be made

without violating the papal decree of 1616. Two of the

conversants -- Salviati and Sagredo -- are sympathetic

to Copernican theory. Simplicio, the third participant,

represents Aristotle and the Scholastics and is

presented as fool. Galileo's enemies were quick to

inform the Pope that the official cosmology of the

Roman Catholic Church had been put in the mouth of

Simplicio. The Pope ordered an investigation and so in

August 1632, less than six months after it had

appeared, the Inquisition banned further sales of the

book. Galileo's book was placed on the Index of

Forbidden Books and there it remained until 1757.

Galileo was ordered to appear before the Inquisition at

Rome. He awaited intervention by the Pope, his former

friend, but it never came. He also believed, quite

innocently, that he could show that Copernicanism was

not in any direct opposition to Church dogma, However,

as Galileo found out, what was at issue was not so much

heliocentricity but authority. Galileo quickly realized

what was at stake. The now seventy year old Galileo

was interrogated relentlessly and threatened with

torture. The Church had a strong defense -- it was clear

that Galileo had violated the prohibition placed upon

him in 1616. He could believe Copernican theory but

not publicly defend it. To prove their position, the

Church produced the forged minutes of Galileo's

meeting with Cardinal Bellarmine in 1616. Unfortunately

for Galileo, by 1632, Bellarmine was dead. The

document produced by the Church was clearly forged. It

acknowledged that Galileo could not hold, teach or

defend Copernican theory in any way. This was a much

stronger prohibition than Galileo could recollect. (See

the Galileo Trial Documents) Without a defense of any

kind, Galileo took his only reasonable option and on

June 22, 1633, he recited the required abjuration on his

knees:

Wishing to remove from the minds of your

Eminences and of every true Christian this

vehement suspicion justly cast upon me, with

sincere heart and unfeigned faith I do abjure, damn,

and detest the said errors and heresies, and

generally each and every other error, heresy and

sect contrary to the Holy Church; and I do swear for

the future that I shall never again speak or assert,

orally or in writing, such things as might bring me

under similar suspicion.

The trial at an end, the abjuration made public, the

broken Galileo spent his remaining eight years under

house arrest at his villa outside Florence. It was at this

time that he wrote perhaps his finest book, the

Dialogues Concerning Two New Sciences, a study of

motion and inertia. His eldest daughter, Sister Marie

Celeste (1600-1634), whom he had sent to a convent

against her wishes twenty-three years earlier, stayed

with him to the end. Every day she said the seven

Psalms of penitence ordered by the Holy Office as part

of his sentence.

Galileo continued to gaze at the stars through his

telescope until 1637, when his sight finally failed him.

"This universe that I have extended one thousand

times," he wrote, "has now shrunk to the narrow

confines of my own body." The trial and condemnation

of Galileo marked the climax of the first wave of the

Scientific Revolution. He had helped to unlock some of

the mysteries of the cosmos for his fellow man.

However, his trial also signified something else. The

weight of papal authority which had brought Galileo to

his knees also succeeded in halting the growth of the

new science in Italy. It is no accident then, that following

Galileo's death in 1642 that the greatest advances in

science would come from outside Italy in countries like

England, Holland and Germany. These were, after all,

Protestant countries with a tradition of protest and

toleration. But 1642 also signifies something else for it

was in that year that the man most responsible for

producing modern science was born. That man was

Isaac Newton (see Lecture 12).