SOCRATES: Then the inference is, that we (the agent and patient) are or
become in relation to one another; there is a law which binds us one to the
other, but not to any other existence, nor each of us to himself; and
therefore we can only be bound to one another; so that whether a person
says that a thing is or becomes, he must say that it is or becomes to or of
or in relation to something else; but he must not say or allow any one else
to say that anything is or becomes absolutely:--such is our conclusion.

THEAETETUS: Very true, Socrates.

SOCRATES: Then, if that which acts upon me has relation to me and to no
other, I and no other am the percipient of it?

THEAETETUS: Of course.

SOCRATES: Then my perception is true to me, being inseparable from my own
being; and, as Protagoras says, to myself I am judge of what is and what is
not to me.

THEAETETUS: I suppose so.

SOCRATES: How then, if I never err, and if my mind never trips in the
conception of being or becoming, can I fail of knowing that which I
perceive?

THEAETETUS: You cannot.

SOCRATES: Then you were quite right in affirming that knowledge is only
perception; and the meaning turns out to be the same, whether with Homer
and Heracleitus, and all that company, you say that all is motion and flux,