and not to them for the solution of the problem.' Well, the doctrine is
old, being derived from the poets, who speak in a figure of Oceanus and
Tethys; the truth was once concealed, but is now revealed by the superior
wisdom of a later generation, and made intelligible to the cobbler, who, on
hearing that all is in motion, and not some things only, as he ignorantly
fancied, may be expected to fall down and worship his teachers. And the
opposite doctrine must not be forgotten:--

'Alone being remains unmoved which is the name for all,'

as Parmenides affirms. Thus we are in the midst of the fray; both parties
are dragging us to their side; and we are not certain which of them are in
the right; and if neither, then we shall be in a ridiculous position,
having to set up our own opinion against ancient and famous men.

Let us first approach the river-gods, or patrons of the flux.

When they speak of motion, must they not include two kinds of motion,
change of place and change of nature?--And all things must be supposed to
have both kinds of motion; for if not, the same things would be at rest and
in motion, which is contrary to their theory. And did we not say, that all
sensations arise thus: they move about between the agent and patient
together with a perception, and the patient ceases to be a perceiving power
and becomes a percipient, and the agent a quale instead of a quality; but
neither has any absolute existence? But now we make the further discovery,
that neither white or whiteness, nor any sense or sensation, can be
predicated of anything, for they are in a perpetual flux. And therefore we
must modify the doctrine of Theaetetus and Protagoras, by asserting further
that knowledge is and is not sensation; and of everything we must say
equally, that this is and is not, or becomes or becomes not. And still the