[Footnote 1: This dramatic introduction is extremely complicated. The whole dialogue, from beginning to end, is recounted by Kephalus of Klazomenæ; who heard it from the Athenian Antiphon--who himself had heard it from Pythodôrus, a friend of Zeno, present when the conversation was held. A string of circumstances are narrated by Kephalus, to explain how he came to wish to hear it, and to find out Antiphon. Plato appears anxious to throw the event back as far as possible into the past, in order to justify the bringing Sokrates into personal communication with Parmenides: for some unfriendly critics tried to make out that the two could not possibly have conversed on philosophy (Athenæus, xi. 505). Plato declares the ages of the persons with remarkable exactness: Parmenides was 65, completely grey-headed, but of noble mien: Zeno about 40, tall and graceful: Sokrates very young. (Plat. Parmen. p. 127 B-C.) It required some invention in Plato to provide a narrator, suitable for recounting events so long antecedent as the young period of Sokrates.] Sokrates is one among various auditors, who are assembled to hear Zeno reading aloud a treatise of his own composition, intended to answer and retort upon the opponents of his preceptor Parmenides. [Side-note: Manner in which the doctrine of Parmenides was impugned. Manner in which his partisan Zeno defended him.] The main doctrine of the real Parmenides was, "That Ens, the absolute, real, self-existent, was One and not many": which doctrine was impugned and derided by various opponents, deducing from it absurd conclusions. Zeno defended his master by showing that the opposite doctrine (--"That Ens, the absolute, self-existent universe, is Many--") led to conclusions absurd in an equal or greater degree. If the Absolute were Many, the many would be both like and unlike: but they cannot have incompatible and contradictory attributes: therefore Absolute Ens is not Many. Ens, as Parmenides conceived it, was essentially homogeneous and unchangeable: even assuming it to be Many, all its parts must be homogeneous, so that what was predicable of one must be predicable of all; it might be all alike, or all unlike: but it could not be both. Those who maintained the plurality of Ens, did so on the ground of apparent severalty, likeness, and unlikeness, in the sensible world. But Zeno, while admitting these phenomena in the sensible world, as _relative to us_, apparent, and subject to the varieties of individual estimation--denied their applicability to absolute and self-existent Ens.[2] Since absolute Ens or Entia are Many (said the opponents of Parmenides), they will be both like and unlike: and thus we can explain the phenomena of the sensible world. The absolute (replied Zeno) cannot be both like and unlike; therefore it cannot be many. We must recollect that both Parmenides and Zeno renounced all attempt to explain the sensible world by the absolute and purely intelligible Ens. They treated