听力原文： [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 But he suggested that the universe was not originally made up of water as Thales had reasoned, but was a living mass, which he called the infinite.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, Anaximanders student Anaximenes, criticized his teachers 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 Lett 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 thats 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, its 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.'Philosophy Class' What is the discussion mainly about?