These, Socrates, said Parmenides, are a few, and only a few of the
difficulties in which we are involved if ideas really are and we
determine each one of them to be an absolute unity. He who hears
what may be said against them will deny the very existence of them-and
even if they do exist, he will say that they must of necessity be
unknown to man; and he will seem to have reason on his side, and as we
were remarking just now, will be very difficult to convince; a man
must be gifted with very considerable ability before he can learn that
everything has a class and an absolute essence; and still more
remarkable will he be who discovers all these things for himself,
and having thoroughly investigated them is able to teach them to
others.

  I agree with you, Parmenides, said Socrates; and what you say is
very much to my mind.

  And yet, Socrates, said Parmenides, if a man, fixing his attention
on these and the like difficulties, does away with ideas of things and
will not admit that every individual thing has its own determinate
idea which is always one and the same, he will have nothing on which
his mind can rest; and so he will utterly destroy the power of
reasoning, as you seem to me to have particularly noted.

  Very true, he said.

  But, then, what is to become of philosophy? Whither shall we turn,
if the ideas are unknown?

  I certainly do not see my way at present.

  Yes, said Parmenides; and I think that this arises, Socrates, out of
your attempting to define the beautiful, the just, the good, and the
ideas generally, without sufficient previous training. I noticed
your deficiency, when I heard you talking here with your friend
Aristoteles, the day before yesterday. The impulse that carries you
towards philosophy is assuredly noble and divine; but there is an
art which is called by the vulgar idle talking, and which is of
imagined to be useless; in that you must train and exercise
yourself, now that you are young, or truth will elude your grasp.

  And what is the nature of this exercise, Parmenides, which you would
recommend?

  That which you heard Zeno practising; at the same time, I give you
credit for saying to him that you did not care to examine the
perplexity in reference to visible things, or to consider the question
that way; but only in reference to objects of thought, and to what may
be called ideas.

  Why, yes, he said, there appears to me to be no difficulty in
showing by this method that visible things are like and unlike and may
experience anything.

  Quite true, said Parmenides; but I think that you should go a step
further, and consider not only the consequences which flow from a
given hypothesis, but also the consequences which flow from denying
the hypothesis; and that will be still better training for you.

  What do you mean? he said.

  I mean, for example, that in the case of this very hypothesis of
Zeno's about the many, you should inquire not only what will be the
consequences to the many in relation to themselves and to the one, and
to the one in relation to itself and the many, on the hypothesis of
the being of the many, but also what will be the consequences to the
one and the many in their relation to themselves and to each other, on
the opposite hypothesis. Or, again, if likeness is or is not, what
will be the consequences in either of these cases to the subjects of
the hypothesis, and to other things, in relation both to themselves
and to one another, and so of unlikeness; and the same holds good of
motion and rest, of generation and destruction, and even of being
and not-being. In a word, when you suppose anything to be or not to
be, or to be in any way affected, you must look at the consequences in
relation to the thing itself, and to any other things which you
choose-to each of them singly, to more than one, and to all; and so of
other things, you must look at them in relation to themselves and to
anything else which you suppose either to be or not to be, if you
would train yourself perfectly and see the real truth.

  That, Parmenides, is a tremendous business of which you speak, and I
do not quite understand you; will you take some hypothesis and go
through the steps?-then I shall apprehend you better.

  That, Socrates, is a serious task to impose on a man of my years.

  Then will you, Zeno? said Socrates.

  Zeno answered with a smile:-Let us make our petition to Parmenides
himself, who is quite right in saying that you are hardly aware of the
extent of the task which you are imposing on him; and if there were
more of us I should not ask him, for these are not subjects which
any one, especially at his age, can well speak of before a large
audience; most people are not aware that this round-about progress
through all things is the only way in which the mind can attain
truth and wisdom. And therefore, Parmenides, I join in the request
of Socrates, that I may hear the process again which I have not
heard for a long time.

  When Zeno had thus spoken, Pythodorus, according to Antiphon's