all of the remaining kinds, and therefore in an infinity of ways 'is not.'
And the argument has shown that the pursuit of contradictions is childish
and useless, and the very opposite of that higher spirit which criticizes
the words of another according to the natural meaning of them. Nothing can
be more unphilosophical than the denial of all communion of kinds. And we
are fortunate in having established such a communion for another reason,
because in continuing the hunt after the Sophist we have to examine the
nature of discourse, and there could be no discourse if there were no
communion. For the Sophist, although he can no longer deny the existence
of not-being, may still affirm that not-being cannot enter into discourse,
and as he was arguing before that there could be no such thing as
falsehood, because there was no such thing as not-being, he may continue to
argue that there is no such thing as the art of image-making and
phantastic, because not-being has no place in language. Hence arises the
necessity of examining speech, opinion, and imagination.

And first concerning speech; let us ask the same question about words which
we have already answered about the kinds of being and the letters of the
alphabet: To what extent do they admit of combination? Some words have a
meaning when combined, and others have no meaning. One class of words
describes action, another class agents: 'walks,' 'runs,' 'sleeps' are
examples of the first; 'stag,' 'horse,' 'lion' of the second. But no
combination of words can be formed without a verb and a noun, e.g. 'A man
learns'; the simplest sentence is composed of two words, and one of these
must be a subject. For example, in the sentence, 'Theaetetus sits,' which
is not very long, 'Theaetetus' is the subject, and in the sentence
'Theaetetus flies,' 'Theaetetus' is again the subject. But the two
sentences differ in quality, for the first says of you that which is true,
and the second says of you that which is not true, or, in other words,
attributes to you things which are not as though they were. Here is false