Str. Very likely, but you may not always think so, my sweet
friend; and in case any feeling of dissatisfaction should hereafter
arise in your mind, as it very well may, let me lay down a principle
which will apply to arguments in general.

  Y. Soc. Proceed.

  Str. Let us begin by considering the whole nature of excess and
defect, and then we shall have a rational ground on which we may
praise or blame too much length or too much shortness in discussions
of this kind.

  Y. Soc. Let us do so.

  Str. The points on which I think that we ought to dwell are the
following:-

  Y. Soc. What?

   Str. Length and shortness, excess and defect; with all of these the
art of measurement is conversant.

  Y. Soc. Yes.

  Str. And the art of measurement has to be divided into two parts,
with a view to our present purpose.

  Y. Soc. Where would you make the division?

  Str. As thus: I would make two parts, one having regard to the
relativity of greatness and smallness to each other; and there is
another, without which the existence of production would be
impossible.

  Y. Soc. What do you mean?

  Str. Do you not think that it is only natural for the greater to
be called greater with reference to the less alone, and the less
reference to the greater alone?

  Y. Soc. Yes.

  Str. Well, but is there not also something exceeding and exceeded by
the principle of the mean, both in speech and action, and is not
this a reality, and the chief mark of difference between good and
bad men?

  Y. Soc. Plainly.

  Str. Then we must suppose that the great and small exist and are
discerned in both these ways, and not, as we were saying before,
only relatively to one another, but there must also be another
comparison of them with the mean or ideal standard; would you like
to hear the reason why?

  Y. Soc. Certainly.

  Str. If we assume the greater to exist only in relation to the less,
there will never be any comparison of either with the mean.

  Y. Soc. True.

  Str. And would not this doctrine be the ruin of all the arts and
their creations; would not the art of the Statesman and the
aforesaid art of weaving disappear? For all these arts are on the
watch against excess and defect, not as unrealities, but as real
evils, which occasion a difficulty in action; and the excellence of
beauty of every work of art is due to this observance of measure.

  Y. Soc. Certainly.

  Str. But if the science of the Statesman disappears, the search
for the royal science will be impossible.

  Y. Soc. Very true.

  Str. Well, then, as in the case of the Sophist we extorted the
inference that not-being had an existence, because here was the
point at which the argument eluded our grasp, so in this we must
endeavour to show that the greater and, less are not only to be
measured with one another, but also have to do with the production
of the mean; for if this is not admitted, neither a statesman nor
any other man of action can be an undisputed master of his science.

  Y. Soc. Yes, we must certainly do again what we did then.

  Str. But this, Socrates, is a greater work than the other, of
which we only too well remember the length. I think, however, that
we may fairly assume something of this sort-

  Y. Soc. What?

  Str. That we shall some day require this notion of a mean with a
view to the demonstration of absolute truth; meanwhile, the argument
that the very existence of the arts must be held to depend on the
possibility of measuring more or less, not only with one another,
but also with a view to the attainment of the mean, seems to afford
a grand support and satisfactory proof of the doctrine which we are
maintaining; for if there are arts, there is a standard of measure,
and if there is a standard of measure, there are arts; but if either