288 Ch. 8 • The New Philosophy Of Science
free of the bonds of tradition, these seventeenth-century thinkers devel
oped the scientific method, a means of understanding based on systematic
observation of natural phenomena and experimentation regarding causes
and effects. But what we now know as the Scientific Revolution owed its
impact less to new technology and inventions than to new ways of thinking
about the universe.
Changing Views of the Universe
The writings of the Greek philosopher Aristotle (384-322 b.c.) dominated
European science for centuries. Then, in the sixteenth century, the Polish
astronomer Copernicus observed the heavens and concluded that ancient
and medieval science could not explain what he saw with his own eyes.
Later in the century, his successors—above all, Galileo—made systematic
mathematical calculations to explain celestial motion. In doing so, they cre
ated scientific methodology, which would also be applied to reach an under
standing of the workings of the human body.
Ancient and Medieval Science
Aristotle believed that the earth was located at or near the center of the
universe. He envisioned a hierarchical order of the cosmos comprised of a
series of spheres that became progressively purer. Aristotle also believed
that terrestrial bodies naturally moved toward the earth, the center of the
universe, unless they were propelled in another direction. In this view,
impetus imparted motion through contact with an object; when the con
tact ceased, the object simply stopped moving or fell back to earth. The
natural tendency of all matter, then, was toward rest, regarded as a nobler
state than motion. Because all motion had to be explained, a “mover”
therefore had to be found for every motion.
In the second century a.d., the Greek astronomer Claudius Ptolemy
(c. 85-165) published a massive work that became known as Almagest (from
the Arabic for “greatest”), which summarized the conclusions of Greek
astronomers and presented his own theories and observations. He described
instruments such as the quadrant, invented by the Arabs, with which he tried
to measure the orbits (which he believed to be spherical) of the sun, moon,
and planets in the sky. Ptolemy accepted Aristotle’s contentions, asserting
that the earth was encased by a series of clear spheres—about eighty—
revolving around it. The most distant sphere contained the farthest stars,
which he believed were fixed points of light. Within those spheres, the moon
was closest to the earth; next came the planets Mars, Venus, Jupiter, and Sat
urn. With minor variations, medieval thinkers still held Ptolemy’s views.
Within the context of Christian theology, people of learning in the Middle
Ages believed that scientific inquiry should serve theological ends through