g and other mutually
interpenetrate; other is, but is other than being, and other than each
and 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 discourse in the shortest form. And thus not only speech,
but thought and opinion and imagination are proved to be both true and
false. For thought is only the process of silent speech, and opinion is
only the silent assent or denial which follows this, and imagination is
only the expre