There are many, but the greatest of all is this:--If an opponent argues
that these ideas, being such as we say they ought to be, must remain
unknown, no one can prove to him that he is wrong, unless he who denies
their existence be a man of great ability and knowledge, and is willing to
follow a long and laborious demonstration; he will remain unconvinced, and
still insist that they cannot be known.

What do you mean, Parmenides? said Socrates.

In the first place, I think, Socrates, that you, or any one who maintains
the existence of absolute essences, will admit that they cannot exist in
us.

No, said Socrates; for then they would be no longer absolute.

True, he said; and therefore when ideas are what they are in relation to
one another, their essence is determined by a relation among themselves,
and has nothing to do with the resemblances, or whatever they are to be
termed, which are in our sphere, and from which we receive this or that
name when we partake of them. And the things which are within our sphere
and have the same names with them, are likewise only relative to one
another, and not to the ideas which have the same names with them, but
belong to themselves and not to them.

What do you mean? said Socrates.

I may illustrate my meaning in this way, said Parmenides:--A master has a
slave; now there is nothing absolute in the relation between them, which is
simply a relation of one man to another. But there is also an idea of