6. The Eleatic School. -- Conceive being in the abstract and universal, endowed with the logical attributes of unity, eternity and immobility; then transfer the object of your concept from the logical to the ontological order; and you have the cosmological system of the School of Elea. But, if everything is reduced to one, immovable, eternal being, how explain the multiple, changeable, ephemeral phenomena of nature? These phenomena, say the Eleatics, do not exist: they are illusions of our senses; and we must take heed only of the findings of reason.
This very decisive conception of things appears only with PARMENIDES (born about 544 or 540). His predecessor, XENOPHANES (576-480), had confined himself to establishing the unity of being, which he identified with God, without, however, denying the coexistence of one unique, substantial substratum for reality, and of a multitude of ephemeral things. In formulating this latter denial, Parmenides gave the Eleatic theory a characteristic attitude and tendency. Everything is: nothing becomes: nothing ceases. Being has neither past nor future; for past and future are not-being, and not-being is irreconcilable with being. All is full: there is no void or emptiness; a vacuum does not exist, for it would introduce a division into being. But being is indivisible, for a thing cannot be separated from itself: it is unchangeable, for it is always equal to itself, one with itself. ZENO OF ELEA, the favourite disciple of Parmenides, was the apologist of the School. He defended the Eleatic theory by showing the contradictions into which those are led who follow the evidence of common sense. His arguments against plurality, and especially against the possibility of movement or motion, are famous for all time.
After MELISSUS, the Eleatic School declined, but the influence of its thought is traceable in Empedocles the Atomist, in the Sophists, and even in Plato and Aristotle.
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