ch is one
and therefore is?

THEAETETUS: That again is true.

SOCRATES: And does not he who thinks, think some one thing?

THEAETETUS: Certainly.

SOCRATES: And does not he who thinks some one thing, think something
which is?

THEAETETUS: I agree.

SOCRATES: Then he who thinks of that which is not, thinks of nothing?

THEAETETUS: Clearly.

SOCRATES: And he who thinks of nothing, does not think at all?

THEAETETUS: Obviously.

SOCRATES: Then no one can think that which is not, either as a
self-existent substance or as a predicate of something else?

THEAETETUS: Clearly not.

SOCRATES: Then to think falsely is different from thinking that which is
not?

THEAETETUS: It would seem so.

SOCRATES: Then false opinion has no existence in us, either in the
sphere of being or of knowledge?

THEAETETUS: Certainly not.

SOCRATES: But may not the following be the description of what we
express by this name?

THEAETETUS: What?

SOCRATES: May we not suppose that false opinion or thought is a sort of
heterodoxy; a person may make an exchange in his mind, and say that one
real object is another real object. For thus he always thinks that which
is, but he puts one thing in place of another; and missing the aim of
his thoughts, he may be truly said to have false opinion.

THEAETETUS: Now you appear to me to have spoken the exact truth: when a
man puts the base in the place of the noble, or the noble in the place
of the base, then he has truly false opinion.

SOCRATES: I see, Theaetetus, that your fear has disappeared, and that
you are beginning to despise me.

THEAETETUS: What makes you say so?

SOCRATES: You think, if I am not mistaken, that your 'truly false' is
safe from censure, and that I shall never ask whether there can be
a swift which is slow, or a heavy which is light, or any other
self-contradictory thing, which works, not according to its own nature,
but according to that of its opposite. But I will not insist upon this,
for I do not wish needlessly to discourage you. And so you are satisfied
that false opinion is heterodoxy, or the thought of something else?

THEAETETUS: I am.

SOCRATES: It is possible then upon your view for the mind to conceive of
one thing as another?

THEAETETUS: True.

SOCRATES: But must not the mind, or thinking power, which misplaces
them, have a conception either of both objects or of one of them?

THEAETETUS: Certainly.

SOCRATES: Either together or in successi