we may speak in the metaphorical language of Plato, became in turn the
tyrant of the mind, the dominant idea, which would allow no other to have a
share in the throne. This is especially true of the Eleatic philosophy:
while the absoluteness of Being was asserted in every form of language, the
sensible world and all the phenomena of experience were comprehended under
Not-being. Nor was any difficulty or perplexity thus created, so long as
the mind, lost in the contemplation of Being, asked no more questions, and
never thought of applying the categories of Being or Not-being to mind or
opinion or practical life.

But the negative as well as the positive idea had sunk deep into the
intellect of man. The effect of the paradoxes of Zeno extended far beyond
the Eleatic circle. And now an unforeseen consequence began to arise. If
the Many were not, if all things were names of the One, and nothing could
be predicated of any other thing, how could truth be distinguished from
falsehood? The Eleatic philosopher would have replied that Being is alone
true. But mankind had got beyond his barren abstractions: they were
beginning to analyze, to classify, to define, to ask what is the nature of
knowledge, opinion, sensation. Still less could they be content with the
description which Achilles gives in Homer of the man whom his soul hates--

os chi eteron men keuthe eni phresin, allo de eipe.

For their difficulty was not a practical but a metaphysical one; and their
conception of falsehood was really impaired and weakened by a metaphysical
illusion.

The strength of the illusion seems to lie in the alternative: If we once
admit the existence of Being and Not-being, as two spheres which exclude
each other, no Being or reality can be ascribed to Not-being, and therefore