"Philosophy Class" What does the professor mean when she says this:

[Narrator] Listen to part of a discussion in a philosophy class.
[Professor]
    The earliest Greek philosophers, also known as the pre-Socratic philosophers, .they were very interested  Q12
in determining the nature of the universe. Initially, Thales proposed that water was the original
material from which all other material was derived, and by that he was referring not only to things on
Earth but also in the heavens. He observed that life sprouts from a moist ground, unlike death that dries
and shrivels into dust. The fact that water could transform itself into a solid as it does when it freezes into
ice or it could change into air as it does when heated into steam, well, this convinced him that everything
had originated as water and would eventually return to water. He believed that all things are living
things, including rocks and metals, and so literally everything would transform itself into the original
material, water, in a logical pattern of change.
    A little later, Anaximander, and he was a student of Thales, so Anaximander was set on a path that
involved questioning which of the elements was the most basic or fundamental. But he suggested that
the universe was not originally made up of water as Thales had reasoned, but was a living mass, which
he called the infinite. The word in Greek actually means "unlimited" but most translators have used the
term infinite since it probably captures the meaning a little better in English. So Anaximander put forward
what some believe is the first theoretical postulate... that the infinite was constantly in motion... up and
down, back and forth. So, although the infinite had begun as a whole, the motion had caused pieces to
be broken off to form all of the elements of the universe... the Earth, the Sun, stars. Then he speculated  Q13
that as the oceans had begun to evaporate, the first sea plants and animals had formed, and from
them their descendants, the birds and land animals evolved, until finally, mankind was created.
[Student 1] That sounds a lot like evolutionary theory.
[Professor]
    Yes, it does. Probably the first instance of evolutionary theory among Europeans, although the Chinese
philosophers had discussed this possibility earlier. Okay, so what do you think he postulated about the
continued motion of the universe? Anyone?
[Student 2]
    I remember that part. He thought that all of these separate elements would eventually be put back
together into the original infinite mass.
[Professor]
    Precisely right. But good students think for themselves, and some years later, Anaximander’s student
Anaximenes, criticized his teacher’s view. He deduced that the original element of the universe was air,
which was timeless and boundless, and in fact, alive. Because mankind and all the animals must
breathe air in order to survive, he believed, therefore, that air had been transformed into blood, bone,
and flesh. He also concluded that air was the origin of water, stone, and earth, and I think you can see
the analogy with the parts of the body there. Furthermore, he contended that the solid condensations of
air constituted the body of the world, but the ethereal quality of air constituted the spirit of the world, and
it was the spirit that remained alive forever.
    Now these three philosophers... Thales, Anaximander, and Anaximenes... they were all residents
of Miletus, and were very active beginning about 600 years before the Christian Era. So they
were called the Milesian philosophers. And they all had different views, but they also had something in
common.
[Student 1]
    Do you mean that they were all materialists? Because they were trying to explain the universe in terms  Q14
of perceivable elements like water and air?
[Professor]
    Good observation Let’t take that a step further. They all attempted to explain the unknown in terms of  Q15
the familiar instead of looking to the current mythologies or to a divine presence. And that’s what is truly
extraordinary about these pre-Socratic philosophers. A naturalistic account of the cosmos was profoundly
different from the myths and legends of gods and goddesses that had been the basis for
explaining the origin of the universe.
[Student 2] So what do you mean by naturalistic?
[Professor]
    I mean that they tried to use scientific arguments, and this marked a very new way of thinking. Unlike the
exciting narratives of superhuman beings with the powers to create and change the universe, they proposed
that the universe was made up of something very basic, and that it was constantly undergoing natural
changes. The Milesians made a major contribution... and they did this by moving beyond the old
mythologies and folktales, and some scholars even suggest that they were responsible for the beginnings
of Western philosophy as we know it. Now when we talk about philosophy, it’s important to point
out that for many centuries philosophy was not a separate discipline from other areas of thought and
knowledge. In fact, early philosophers were mathematicians, physicists, chemists, and biologists before
any of these sciences were identified as separate, uh...  subjects, or... fields of study. So the pre-Socratic  Q16
philosophers were trying to discover a scientific basis for the universe tong before the scientific
method and the technologies were available to support their investigations. But, really, many scholars
argue that these philosophers did initiate the process at least, and the process eventually resulted...
years later... as the beginning of the physical sciences.
    Okay, all of this appears on the surface to be very positive, right? But at the time, many philosophers  Q17
as well as ordinary citizens were feeling much less comfortable with the very sparse tenants of
emerging science than they had been with the rich and complicated stories that had explained the universe
for them. Remember that this is all before Socrates, Aristotle, and Plato who were... by then...
well, more able to expand on protoscientific thought and produce a massive and elaborate scientific
alternative to the ancient beliefs.