theory of knowledge. The time at which such a theory could be framed had
not yet arrived. For there was no measure of experience with which the
ideas swarming in men's minds could be compared; the meaning of the word
'science' could scarcely be explained to them, except from the mathematical
sciences, which alone offered the type of universality and certainty.
Philosophy was becoming more and more vacant and abstract, and not only the
Platonic Ideas and the Eleatic Being, but all abstractions seemed to be at
variance with sense and at war with one another.

The want of the Greek mind in the fourth century before Christ was not
another theory of rest or motion, or Being or atoms, but rather a
philosophy which could free the mind from the power of abstractions and
alternatives, and show how far rest and how far motion, how far the
universal principle of Being and the multitudinous principle of atoms,
entered into the composition of the world; which could distinguish between
the true and false analogy, and allow the negative as well as the positive
a place in human thought. To such a philosophy Plato, in the Theaetetus,
offers many contributions. He has followed philosophy into the region of
mythology, and pointed out the similarities of opposing phases of thought.
He has also shown that extreme abstractions are self-destructive, and,
indeed, hardly distinguishable from one another. But his intention is not
to unravel the whole subject of knowledge, if this had been possible; and
several times in the course of the dialogue he rejects explanations of
knowledge which have germs of truth in them; as, for example, 'the
resolution of the compound into the simple;' or 'right opinion with a mark
of difference.'

...

Terpsion, who has come to Megara from the country, is described as having