SOCRATES: And can we say that any of these things which neither are nor have been nor will be unchangeable, when judged by the strict rule of truth ever become certain?
PROTARCHUS: Impossible.
SOCRATES: How can anything fixed be concerned with that which has no fixedness?
PROTARCHUS: How indeed?
SOCRATES: Then mind and science when employed about such changing things do not attain the highest truth?
PROTARCHUS: I should imagine not.
SOCRATES: And now let us bid farewell, a long farewell, to you or me or Philebus or Gorgias, and urge on behalf of the argument a single point.
PROTARCHUS: What point?
SOCRATES: Let us say that the stable and pure and true and unalloyed has to do with the things which are eternal and unchangeable and unmixed, or if not, at any rate what is most akin to them has; and that all other things are to be placed in a second or inferior class.
PROTARCHUS: Very true.