But what can we say of the varied world of nature as it appears to us? Do we see, hear, and touch many things and motions? In Part II of his poem he raises the question, Suppose man takes the world of change as real how must he explain it? He answers by using the explanation of Heracleitus. But these changes of eye and ear belong to the world of sense, and Parmenides is talking, in Part I of his poem, about the real world or that world known to thought. Parmenides insists as strongly as did Heracleitus that the reason and not the sense shall be our guide to what is real. Yet he arrives at exactly the opposite conclusion from Heracleitus as to what the reason sees as real. The senses show us only the many and the changing. The reason shows us nothing of the sort, but only permanence and unchangingness. b. =Zeno= (b. 490–430 B. C.). Zeno was born in Elea. He was contemporary with those who tried to reconcile the two sides of the metaphysical controversy,――Empedocles, Anaxagoras, and the Atomists. He wrote in prose in the form of question and answer. This is the beginning of the dialogue literature, which in the time of the Sophists, Socrates and Plato, was richly developed and became known as dialectic. On the Greek stage during the time of Pericles it came forth in dramatic form through Æschylus, Sophocles, and Euripides. =The Philosophy of Zeno.= Zeno was the active controversialist of the school of Elea, and he was not a constructive philosopher. He offered no contribution to advance the thought of Parmenides. He appeared rather as the master of logical argument in defense of his predecessor, by tearing to pieces the arguments of his opponents. The opponents that Zeno is attacking are the Atomists of Abdera, who were his contemporaries, rather than Heracleitus. His contribution was negative and formal, but it was nevertheless effective and searching. His arguments and paradoxes will, however, lose their cogency unless it be kept in mind that he is trying to show how absurd magnitude, multiplicity, and change would be in discontinuous space such as the Atomists describe. While his paradoxes have been attacked again and again, they still have effectiveness against atomic theories. His arguments are against magnitude, multiplicity, and motion. There can be no magnitude, because a thing would then be both infinitely small and infinitely great. There can be no multiplicity of things, since they would be both limited and unlimited in number. There can be no motion, because (1) it is impossible to go through a fixed space; (2) it is impossible to go though a space that has movable limits; and (3) because of the relativity of motion. The dilemmas which he proposed of Achilles and the tortoise, the flying arrow at rest, and the bushel of corn are classic.[10]