From the immense importance attached by Parmenides to the verb ἐστί, and from his assertion that men deal with names and not with realities, it followed that to his metaphysical teaching a logical set of corollaries had to be appended. To construct these was the task of Zeno, his beloved pupil and authorized successor. Zeno undertook to maintain the Parmenidean Unity, both against the vulgar evidence of the senses and also against philosophers who, like Heraclitus, directed their attention to the flux and multiplicity of things. His method was, not to prove the necessity of unity at rest, but to demonstrate the contradictions involved in the ideas of plurality and motion. The intellectual difficulties implied in the divisibility of time and space and matter were developed by Zeno with a force and subtlety that justified Aristotle in calling him the founder of dialectic. His logic, however, was but the expansion of positions implicit in Xenophanes and clearly indicated by Parmenides. How the Eleatic arguments, as further handled by Melissus, helped the Sophists, and influenced the school of Megara, who went so far as to refuse any but identical propositions, are matters that belong to another chapter of Greek history. So, too, is Plato's attempt to resolve the antinomies revealed in human thought by the polemic of his predecessors. Enough has now been said to serve as preface to the following version of the fragments of Parmenides.
His poem—for, strange as it must always seem, Parmenides committed the exposition of his austerely abstract and argumentative doctrine to hexameters—begins with an epical allegory. He feigns to have been drawn by horses on a chariot to the house of Truth: the horses may, perhaps, be taken, as in Plato's vision of the Phædrus, to symbolize faculties of the soul; and the gates of Truth open upon two roads—one called the way of night, or error; the other, of light, or real knowledge. The goddess who dwells here, divine Sophia, instructs him equally in the lore of truth and of opinion, and makes no attempt, as will be seen from her own words, to conceal the futility of the second part of her discourse. From a literary point of view the poem has no merit. Even the exordium is stiff and tame. It begins thus:
"The steeds which bear me, and have brought me to the bounds of my desire, since they drew and carried me into the way renowned of her who leads the wise man to all knowledge—on that road I journeyed, on that road they bore me, those steeds of thought that whirl the car along. But maidens showed the way, sun-born maids, who left the halls of gloom and brought us to the light, withdrawing with their fingers from their brows the veils. And the axle in the socket made a whistling sound, glowing as by two round wheels on either side it ran, while the steeds drove the car swiftly on. There are the gates which open on the paths of Night and Day. A lintel shuts them in above, and a floor of stone beneath; but the airy space they close is fastened with huge doors, which Justice the avenger locks or unlocks by the key she holds. Her did the maidens sue with gentle words, and wisely won her to draw for them the bolted barrier from the gates. The gates flew open, and the doors yawned wide, back rolling in the sockets their brazen hinges wrought with clasps and nails. Straight through the portal drove the maidens car and horses on the broad highway. And me the goddess graciously received; she took my right hand in her hand, and spoke these words, addressing me: 'Child of man, companion of immortal charioteers, that comest drawn by horses to our home, welcome! for thee no evil fate sent forth to travel on this path—far from the track of men indeed it lies—but Right and Justice were thy guides. Thy lot it is all things to learn; both the sure heart of truth that wins assent, and the vain fancies of mortals which have no real ground of faith. Yet these, too, shalt thou learn, since it behooves thee to know all opinions, testing them, and travelling every field of thought.'"
Here the exordium, as we possess it, ends, and we start upon the fragments of the lecture addressed by divine Sophia to the mortal sage. The order and the connection of these fragments are more than doubtful. So much, however, is clear, that they fall into two sections—the first treating of scientific truth, the second of popular opinion. The instrument of knowledge in the one case is the reason; in the other the senses bear confused and untrustworthy witness to phenomena.
"Come now, for I will tell, and do thou hear and keep my words, what are the only ways of inquiry that lead to knowledge. The one which certifies that being is, and that not-being is not, is the pathway of persuasion, for truth follows it. The other, which declares that being is not, and that not-being must be, that I affirm is wholly unpersuasive; for neither couldst thou know not-being, since it cannot be got at, nor couldst thou utter it in words, seeing that thought and being are the same.
"To me it is indifferent where I begin, for again to the same point I shall return. It must be that speech and thought are being, for being is, and that not-being is nothing: which things I bid thee ponder. First, keep thy mind from that path of inquiry, then, too, from that on which mortals who know nothing wander in doubt; helplessness sways in their breasts the erring mind; hither and thither are they borne, deaf, yea, and blind, in wonderment, confused crowds who fancy being and not-being are the same and not the same; the way of all of them leads backwards."
Some light is thrown upon these fragments by a passage in the Sophistes of Plato, where the Eleatic stranger is made to say: "In the days when I was a boy, the great Parmenides protested against this (i.e., against asserting the existence of not-being), and to the end of his life he continued to inculcate the same lesson—always repeating, both in verse and out of verse, Keep your mind from this way of inquiry, for never will you show that not-being is." The fragment which immediately follows, if we are right in assuming the continuity and order of its verses, forms the longest portion of the poem extant.
"Never do thou learn to fancy that things that are not, are; but keep thy mind from this path of inquiry; nor let custom force thee to pursue that beaten way, to use blind eyes and sounding ear and tongue, but judge by reason the knotty argument which I declare. One only way of reasoning is left—that being is. Wherein are many signs that it is uncreate and indestructible, whole in itself, unique in kind, immovable and everlasting. It never was, nor will be, since it exists as a simultaneous present, a continuous unity. What origin shall we seek of it? Where and how did it grow? That it arose from not-being I will not suffer thee to say or think, for it cannot be thought or said that being is not. Then, too, what necessity could have forced it to the birth at an earlier or later moment? for neither birth nor beginning belongs to being. Wherefore either to be or not to be is the unconditioned alternative. Nor will the might of proof allow us to believe that anything can spring from being but itself. Therefore the law of truth permits no birth or dissolution in it, no remission of its chains, but holds it firm. This, then, is the point for decision: it is, or it is not. Now we have settled, as necessity obliged, to leave the one path, inconceivable, unnamed, for it is not the true way; but to affirm, as sure, that being is. How then could being have a future or a past? If it began to be, or if it is going to be, then it is not: wherefore birth and death are alike put aside as inconceivable. Nor is it divisible, since it is all homogeneous, in no part more itself than in another, which would prevent its coherence, nor in any part less; but all is full of being. Wherefore it is one continuous whole, for being draws to being. Immovable within the bounds of its great chains it is, without beginning, without end, since birth and dissolution have moved far away, whom certainty repelled. Eternally the same, in the same state, for and by itself, it abides; thus fixed and firm it stays, for strong necessity holds it in the chains of limit and clinches it around. Wherefore being cannot be infinite, seeing it lacks nothing; and if it were, it would lack all.
"Look now at things which, though absent, are present to the mind. For never shall being from being be sundered so as to lose its continuity by dispersion or recombination.
"Thought and the object of thought are the same, for without being, in which is affirmation, thou wilt not find thought. For nothing is or will be besides being, since fate hath bound it to remain alone and unmoved, which is named the universe—all things that mortal men held fixed, believing in their truth—birth and death, to be and not to be, change of place, and variety of color.