such as he perceives them?

THEAETETUS: Yes.

SOCRATES: Then perception is always of existence, and being the same as
knowledge is unerring?

THEAETETUS: Clearly.

SOCRATES: In the name of the Graces, what an almighty wise man
Protagoras must have been! He spoke these things in a parable to the
common herd, like you and me, but told the truth, 'his Truth,' (In
allusion to a book of Protagoras' which bore this title.) in secret to
his own disciples.

THEAETETUS: What do you mean, Socrates?

SOCRATES: I am about to speak of a high argument, in which all things
are said to be relative; you cannot rightly call anything by any name,
such as great or small, heavy or light, for the great will be small and
the heavy light--there is no single thing or quality, but out of motion
and change and admixture all things are becoming relatively to one
another, which 'becoming' is by us incorrectly called being, but is
really becoming, for nothing ever is, but all things are becoming.
Summon all philosophers--Protagoras, Heracleitus, Empedocles, and the
rest of them, one after another, and with the exception of Parmenides
they will agree with you in this. Summon the great masters of either
kind of poetry--Epicharmus, the prince of Comedy, and Homer of Tragedy;
when the latter sings of

'Ocean whence sprang the gods, and mother Tethys,'

does he not mean that all things are the offspring, of flux and motion?

THEAETETUS: I think so.

SOCRATES: And who could take up arms against such a great army having
Homer for its general, and not appear ridiculous? (Compare Cratylus.)

THEAETETUS: Who indeed, Socrates?

SOCRATES: Yes, Theaetetus; and there are plenty of other proofs
which will show that motion is the source of what is called being and
becoming, and inactivity of not-being and destruction; for fire and
warmth, which are supposed to be the parent and guardian of all other
things, are born of movement and of friction, which is a kind of
motion;--is not this the origin of fire?

THEAETETUS: It is.

SOCRATES: And the race of animals is generated in the same way?

THEAETETUS: Certainly.

SOCRATES: And is not the bodily habit spoiled by rest and idleness, but
preserved for a long time by motion and exercise?

THEAETETUS: True.

SOCRATES: And what of the mental habit? Is not the soul informed, and
improved, and preserved by study and attention, which are motions; but
when at rest, which in the soul only means want of at