Copernicus, Nicolaus, «koh PUR nuh kuhs, NIHK uh LAY uhs» (1473-1543), a Polish
astronomer, developed the theory that Earth is a moving planet. He claimed that Earth and the
other planets revolve around the sun, which he considered to be motionless. Astronomers now
know that the sun is just one of many stars orbiting the center of our galaxy. But Copernicus’s
ideas about the roles of the sun and planets were essentially correct. He is considered the
founder of modern astronomy.
Theories of heavenly motion. In Copernicus's time, most astronomers thought that Earth
was the center of the universe and stayed motionless. The Greek astronomer Ptolemy had
developed this idea in the A.D. 100's. According to Ptolemy’s theory, the other heavenly bodies
moved around Earth. But the theory struggled to explain certain irregular motions of the
planets across the sky.
Copernicus sought the simplest and most systematic explanation of heavenly motion. He
realized that it required that every planet, including Earth, revolve around the sun.
Galileo, «GAL uh LAY oh or GAL uh LEE oh» (1564-1642), an Italian astronomer, has been
called a founder of modern experimental science. In 1609, Galileo made the first effective use
of the refracting telescope to discover important new facts about astronomy. He also
discovered the law of falling bodies.
He gained his first public notice with his new hydrostatic balance. The balance was an
instrument used to find the specific gravity of objects by weighing them in water.
Mature scientific career. In 1609, while still at Padua, Galileo built his first telescope.
Turning it to the sky, he saw clear evidence that many of Aristotle's and Ptolemy's claims
about the heavens were false. Galileo's first discovery was that the moon is not perfectly
smooth, as Aristotle and Ptolemy had thought. Instead, the moon was mountainous and pitted,
much like Earth.
Among the most important results of this search were the law of the pendulum and the law of
freely falling bodies. Galileo observed that pendulums of equal length swing at the same rate
whether their arcs are large or small. Modern measuring instruments show that the rate is
actually somewhat greater if the arc is large. Galileo's law of falling bodies states that all
objects fall at the same speed, regardless of their mass.
Galileo was seen as a problem by the Catholic Church for his views which went against the
church’s beliefs about the earth and heavens. He was put on trial but because of his advanced
age he was allowed to serve his sentence under house arrest. He died under house arrest.
Locke, John (1632-1704), was an English philosopher. His writings have influenced
political science and philosophy. Locke's book Two Treatises of Government (1690) strongly
influenced Thomas Jefferson in the writing of the Declaration of Independence.
His philosophy. Locke's major work was An Essay Concerning Human Understanding (1690).
It describes his theory of how the mind functions in learning about the world. Locke argued
against the doctrine of innate ideas, which stated that ideas were part of the mind at birth and
not learned or acquired later from outside sources. Locke claimed that all ideas were placed in
the mind by experience. He declared that there were two kinds of experience, outer and inner.
Outer experience was acquired through the senses of sight, taste, hearing, smell, and touch,
which provide information about the external world. Inner experience was acquired by thinking
about the mental processes involved in sifting these data, which furnished information about
the mind.
Locke believed that people by nature had certain rights and duties. These rights included
liberty, life, and ownership of property. By liberty, Locke meant political equality. The task of
any state (country) was to protect people's rights. States inconvenience people in various
ways. Therefore, the justification for a state's existence had to be found in its ability to protect
human rights better than individuals could on their own. Locke declared that if a government
did not adequately protect the rights of its citizens, they had the right to find other rulers.
Newton, Sir
Isaac (1642-1727), an English scientist, astronomer, and mathematician,
invented a new kind of mathematics, discovered the secrets of light and color, and showed
how the universe is held together.
Newton discovered how the universe is held together through his theory of gravitation. He
discovered the secrets of light and color. He invented a branch of mathematics, calculus.
Newton made these three discoveries within 18 months from 1665 to 1667.
The theories of motion and gravitation. Newton said the concept of a universal force came
to him while he was alone in the country. He had been forced to flee there because of the
outbreak of plague in the city of Cambridge. During this time, Newton realized that one and
the same force pulls an object to Earth and keeps the moon in its orbit. He found that the force
of universal gravitation makes every pair of bodies in the universe attract each other. The
force depends on (1) the amount of matter in the bodies being attracted and (2) the distance
between the bodies. For instance, the force by which Earth attracts or pulls a large rock is
greater than its pull on a small pebble because the rock contains more matter. Earth's pull is
called the weight of the body. With this theory, Newton explained why a rock weighs more
than a pebble.
By passing a beam of sunlight through a glass prism and studying the colors that were
produced, Newton discovered that sunlight is a mixture of light of all colors. According to this
model of light, a green sweater looks green in sunlight because it largely reflects the green
light in the sun and absorbs most of the other colors. If the green sweater were lighted by a
red light or any color light not containing green, it would not appear green.
The study of light led Newton to consider constructing a new type of telescope in which a
reflecting mirror was used instead of a combination of lenses. Newton's first reflecting
telescope was 6 inches (15 centimeters) long, and, through it, Newton saw the satellites of
Jupiter.
Voltaire,
«vol TAR or vohl TAR» (1694-1778), was the pen name of Francois Marie
Arouet, a French author and philosopher. Voltaire's clear style, sparkling wit, keen intelligence,
and strong sense of justice made him one of France's most famous writers.
Candide (1759), Voltaire's best-known work, is a brilliant philosophical tale that has been
translated into more than 100 languages. On the surface, the work describes the adventures of
an inexperienced young man as he wanders around the world but it is really about the nature
of good and evil.
Imprisonment and early success. In 1717, Voltaire was imprisoned in the Bastille for
satirical verses that he may or may not have written ridiculing the government. During his 11
months in prison, he finished his tragedy Oedipe. The success of the play in 1718 made
Voltaire the greatest French playwright of his time. He maintained this reputation—with more
than 50 plays—for the rest of his life. While in prison, Voltaire also worked on La Henriade, an
epic poem about King Henry IV. He was later exiled for making fun of a French noble.
The Roman Catholic Church, because of much criticism by Voltaire, refused to allow him to be
buried in church ground. However, his body was finally taken to an abbey in Champagne. In
1791, Voltaire's remains were transferred to the Pantheon in Paris, where many of France's
greatest are buried.
Descartes, Rene, «day KAHRT, ruh NAY» (1596-1650), was a French philosopher,
mathematician, and scientist. He is often called the father of modern philosophy. Descartes
invented analytic geometry and developed a detailed account of the physical universe in terms
of matter and motion. He was a pioneer in the attempt to formulate simple, universal laws of
motion that govern all physical change.
His philosophy. Descartes is called a dualist because he claimed that the world consists of
two basic substances—matter and spirit. Matter is the physical universe, of which our bodies
are a part. The human mind, or spirit, interacts with the body
In one of his works, Descartes introduced the famous Latin phrase cogito ergo sum, which
means I think, therefore I am.
Montesquieu,
«MON teh SKYOO» (1689-1755), was a French philosopher. His
major work, The Spirit of the Laws (1748), influenced the writing of many constitutions,
including the Constitution of the United States.
Montesquieu said there were three basic types of government—monarchal, republican, and
despotic. A monarchal government had limited power placed in a king or queen. A republican
government was either an aristocracy or a democracy. In an aristocracy, only a few had
power. In a democracy, all had it. A despotic government was controlled by a tyrant, who had
absolute authority. Montesquieu believed legal systems should vary according to the basic type
of government.
Montesquieu supported human freedom and opposed tyranny. He believed that political liberty
involved separating the legislative, executive, and judicial powers of government. He believed
that liberty and respect for properly constituted law could exist together.
Rousseau, Jean-Jacques,
«roo SOH, jhahn zhahk» (1712-1778), was a French
philosopher. He was the most important writer of the Enlightenment, a period of European
history that extended from the late 1600's to the late 1700's. Rousseau's philosophy helped
shape the political events that led to the French Revolution. His works have influenced
education, literature, and politics.
The turning point in Rousseau's life came in 1749, when he read about a contest sponsored by
the Academy of Dijon. The academy was offering a prize for the best essay on the question of
if the rebirth of art and science was helping make people in society better people. As he read
about the contest, Rousseau realized the course his life would take. He would oppose the
existing social structure, spending the rest of his life indicating new directions for social
development. Rousseau submitted an essay to the academy. His "Discourse on the Sciences
and the Arts" (1750 or 1751) attacked the arts and sciences for corrupting humanity (making
people worse). He won the prize and the fame he had so long desired.
His ideas. Rousseau criticized society in several essays. For example, in "Discourse on the
Origin and Foundations of Inequality" (1755), he attacked society and private property as
causes of inequality and oppression.
Rousseau believed that people are not social beings by nature. He stated that people, living in
a natural condition, isolated and without language, are kind and without motive or impulse to
hurt one another. However, once they live together in society, people become evil. Society
corrupts individuals by bringing out their inclination toward aggression and selfishness.