on?

THEAETETUS: Very good.

SOCRATES: And do you mean by conceiving, the same which I mean?

THEAETETUS: What is that?

SOCRATES: I mean the conversation which the soul holds with herself in
considering of anything. I speak of what I scarcely understand; but the
soul when thinking appears to me to be just talking--asking questions
of herself and answering them, affirming and denying. And when she has
arrived at a decision, either gradually or by a sudden impulse, and has
at last agreed, and does not doubt, this is called her opinion. I
say, then, that to form an opinion is to speak, and opinion is a word
spoken,--I mean, to oneself and in silence, not aloud or to another:
What think you?

THEAETETUS: I agree.

SOCRATES: Then when any one thinks of one thing as another, he is saying
to himself that one thing is another?

THEAETETUS: Yes.

SOCRATES: But do you ever remember saying to yourself that the noble
is certainly base, or the unjust just; or, best of all--have you ever
attempted to convince yourself that one thing is another? Nay, not even
in sleep, did you ever venture to say to yourself that odd is even, or
anything of the kind?

THEAETETUS: Never.

SOCRATES: And do you suppose that any other man, either in his senses
or out of them, ever seriously tried to persuade himself that an ox is a
horse, or that two are one?

THEAETETUS: Certainly not.

SOCRATES: But if thinking is talking to oneself, no one speaking and
thinking of two objects, and apprehending them both in his soul, will
say and think that the one is the other of them, and I must add, that
even you, lover of dispute as you are, had better let the word 'other'
alone (i.e. not insist that 'one' and 'other' are the same (Both words
in Greek are called eteron: compare Parmen.; Euthyd.)). I mean to say,
that no one thinks the noble to be base, or anything of the kind.

THEAETETUS: I will give up the word 'other,' Socrates; and I agree to
what you say.

SOCRATES: If a man has both of them in his thoughts, he cannot think
that the one of them is the other?

THEAETETUS: True.

SOCRATES: Neither, if he has one of them only in his mind and not the
other, can he think that one is the other?

THEAETETUS: True; for we should have to suppose that he apprehends that
which is not in his thoughts at all.

SOCRATES: Then no one who has either both or only one of the two objects
in his mind can think that the one is the other. And therefore, he