The philosophers observed with their own eyes that nature was in a
constant state of transformation. But how could such transformations occur?
How could something change from being substance to being a living
thing, for example?
All the earliest philosophers shared the belief that there had to be a
certain basic substance at the root of all change. How they arrived at this idea
is hard to say. We only know that the notion gradually evolved that there must
be a basic substance that was the hidden cause of all changes in nature.
There had to be “something” that all things came from and returned to.
For us, the most interesting part is actually not what solutions these
earliest philosophers arrived at, but which questions they asked and what type
of answer they were looking for. We are more interested in how they thought
than in exactly what they thought.
We know that they posed questions relating to the transformations they
could observe in the physical world. They were looking for the underlying laws
of nature. They wanted to understand what was happening around them
without having to turn to the ancient myths. And most important, they wanted
to understand the actual processes by studying nature itself. This was quite
different from explaining thunder and lightning or winter and spring by telling
stories about the gods.
So philosophy gradually liberated itself from religion. We could say that
the natural philosophers took the first step in the direction of scientific
reasoning, thereby becoming the precursors of what was to become science.
Only fragments have survived of what the natural philosophers said and
wrote. What little we know is found in the writings of Aristotle, who lived two
centuries later. He refers only to the conclusions the philosophers reached.
So we do not always know by what paths they reached these conclusions. But
what we do know enables us to establish that the earliest Greek philosophers’
project concerned the question of a basic constituent substance and the
changes in nature.
THREE PHILOSOPHERS FROM MILETUS
The first philosopher we know of is Thales, who came from Miletus, a
Greek colony in Asia Minor. He traveled in many countries, including Egypt,
where he is said to have calculated the height of a pyramid by measuring its
shadow at the precise moment when the length of his own shadow was equal
to his height. He is also said to have accurately predicted a solar eclipse in
the year 585 B.C.
Thales thought that the source of all things was water. We do not know
exactly what he meant by that, he may have believed that all life originated
from water—and that all life returns to water again when it dissolves.
During his travels in Egypt he must have observed how the crops began
to grow as soon as the floods of the Nile receded from the land areas in the
Nile Delta. Perhaps he also noticed that frogs and worms appeared wherever
it had just been raining.
It is likely that Thales thought about the way water turns to ice or
vapor—and then turns back into water again.
Thales is also supposed to have said that “all things are full of gods.”
What he meant by that we can only surmise. Perhaps, seeing how the black
earth was the source of everything from flowers and crops to insects and