Thales of Miletus, founder of Western Science
It was Thales of Miletus who began the quest to discover the natural causes that regulate the physical universe. Though he and his Greek successors made mistakes along the way and some of their understandings of the universe have been proven invalid, given the state of primitive technology at their disposal they can be easily forgiven. Indeed the Greeks identified and clearly stated for later scientists many of the fundamental problems of science that are still studied today, such issues as the constituents of matter, the nature of change, the movement of the planets, reproduction, and heredity. More importantly, Thales and his successors developed the scientific outlook and the first aspects of the scientific methodology that have enabled modern scientists to do their work.
Thales in context
Thales (625-546 B.C.E) has often been called the "Father of Philosophy." Philosophia is a Greek word meaning, "love of wisdom." And Greek philosophers were not merely what we call philosophers today -- those that study metaphysics, ethics, logic, epistemology, and so on -- but were also scientists, political theorists, even poets. No branch of knowledge was excluded from consideration. The concept of academic specialization, to the ancients, was alien. Greek philosophers were the original "Renaissance men" -- in fact, it was the later literal Renaissance men who modeled the earlier Greeks and Romans.
The Greek city-states stood in sharp contrast to their Near Eastern counterparts, where science was the exclusive province of a powerful class of priests who had inherited their positions and whose economic and ideological reliance on their religion and its dogmas invariably hindered inquiry. Greek philosophers, by contrast, were laymen, for whom science was an avocation. In general, philosophers were free to act independently and considered all questions open to debate.
It may not have been an accident that Miletus, the leading center of trade in Ionia, was the birthplace of philosophy. The Greeks of Miletus traded with the Phoenicians, Lydians, Egyptians, and Miletus's own colonies in the Mediterranean and Black Seas, which numbered around seventy. It was this interaction with other cultures which encouraged a willingness to depart from conventional patterns of thought. A good amount of cultural diffusion and ideas being shared didn't hurt either.
Thales was the first to emphasize the role of physical laws in the operation of the universe. Though most Greeks never shared this emphasis, and even Thales himself believed in omnipotent and immortal Gods, it was his insistence on emphasizing the explanatory power of these physical operations that proved essential to the progress of science. Until this point mythological explanations of natural occurrences were the only explanations which were accepted. For example, Zeus was the progenitor of thunder, in fact one his epithets was "Zeus Brontios" or "Zeus the Thunderer" and it was understood that this was an effect of his divine power. Of course, our modern understand is that thunder is a result of the rapid expansion of air around a lightning bolt, similar to a sonic boom. In fact, it was Thales intellectual successor Aristotle who first proposed that thunder was the result of clouds colliding with one another, and not the result of an angry god.
According to Herodotus, Thales collected sufficient astronomical knowledge to predict a total solar eclipse during the year 585 B.C.E., to determine the solstices, and to divide the year into 365 days. Thales knew enough geometry to calculate the distance of a ship at sea from the shoreline, and how to calculate the height of an object based on its shadow. He made the famous statements:
"Virtue is refraining from doing what we blame in others," and
"The whole world is the native country of a wise man."
One story about Thales alleges that he was looking up so intently at the sky one day that he fell into a well (the beginning of the eccentric professor stereotype), but Aristotle relates a more plausible tale concerning the ancient scientist. According to Aristotle, Thales was being criticized by his fellow citizens for wasting time on idle pursuits like science, or attempting to come up with alternative explanations to natural phenomenon. He decided he'd teach his fellow citizens a lesson and used his knowledge to predict a bumper olive crop. Thales bought up all the olive-presses in Miletus and neighboring city-states -- since olive presses were used to process olives into olive oil. Sure enough, Thales made a fortune as everyone had to come to him process their olive crops. Thales made his point: that even a seemingly idle pursuit like philosophy could be used to make money, if one considered it worth the effort.
A Lasting Paradigm
Like all scientists, ancient and modern, Thales was not immune from error. Thales greatest mistake, in retrospect, was his contention that the earth was composed of water on which land floated. The Egyptians advanced the same theory, though theirs was religiously based. By contrast Thales based his theory on logic, however faulty, as he believed water was a special substance because it existed in all three physical states and was vital to all organisms. The foundation for Thales' error was the belief in a simple universe that only seemed complex, a belief that was shared by most Greek philosophers. However, even if sometimes in error, Thales major contribution was the paradigm he founded. One in which explanations were not religiously based, or proposed by priests with conflicting interests, but were based on logical physical explanations. This eventually, through the centuries, paved the way for our modern understanding of science.