of them. The Parmenides belongs to that stage of the dialogues of Plato in
which he is partially under their influence, using them as a sort of
'critics or diviners' of the truth of his own, and of the Eleatic theories.
In the Theaetetus a similar negative dialectic is employed in the attempt
to define science, which after every effort remains undefined still. The
same question is revived from the objective side in the Sophist: Being and
Not-being are no longer exhibited in opposition, but are now reconciled;
and the true nature of Not-being is discovered and made the basis of the
correlation of ideas. Some links are probably missing which might have
been supplied if we had trustworthy accounts of Plato's oral teaching.

To sum up: the Parmenides of Plato is a critique, first, of the Platonic
Ideas, and secondly, of the Eleatic doctrine of Being. Neither are
absolutely denied. But certain difficulties and consequences are shown in
the assumption of either, which prove that the Platonic as well as the
Eleatic doctrine must be remodelled. The negation and contradiction which
are involved in the conception of the One and Many are preliminary to their
final adjustment. The Platonic Ideas are tested by the interrogative
method of Socrates; the Eleatic One or Being is tried by the severer and
perhaps impossible method of hypothetical consequences, negative and
affirmative. In the latter we have an example of the Zenonian or Megarian
dialectic, which proceeded, not 'by assailing premises, but conclusions';
this is worked out and improved by Plato. When primary abstractions are
used in every conceivable sense, any or every conclusion may be deduced
from them. The words 'one,' 'other,' 'being,' 'like,' 'same,' 'whole,' and
their opposites, have slightly different meanings, as they are applied to
objects of thought or objects of sense--to number, time, place, and to the
higher ideas of the reason;--and out of their different meanings this
'feast' of contradictions 'has been provided.'