things are
beautiful, but what is beauty. I did not ask for many things, but for
one thing, namely, beauty. If beauty is a rose, it cannot be
moonlight, because a rose and moonlight are quite different things. By
beauty we mean, not many things, but one. This is proved by the fact
that we use only one word for it. And what I want to know is what this
one beauty is, which is distinct from all beautiful objects. Perhaps
you will say that there is no such thing as beauty apart from
beautiful objects, and that, though we use one word, yet this is only
a manner of {185} speech, and that there are in reality many beauties,
each residing in a beautiful object. In that case, I observe that,
though the many beauties are all different, yet, since you use the one
word to describe them all, you evidently think that they are similar
to each other. How do you know that they are similar? Your eyes cannot
inform you of this similarity, because it involves comparison, and we
have already seen that comparison is an act of the mind, and not of
the senses. You must therefore have an idea of beauty in your mind,
with which you compare the various beautiful objects and so recognise
them as all resembling your idea of beauty, and therefore as
resembling each other. So that there is at any rate an idea of one
beauty in your mind. Either this idea corresponds to something outside
you, or it does not. In the latter case, your idea of beauty is a mere
invention, a figment of your own brain. If so, then, in judging
external objects by your subjective idea, and in making it the
standard of whether they are beautiful or not, you are back again at
the position of the Sophists. You are making yourself and the fancies
of your individual brain the standard of external truth. Therefore,
the only alternative is to believe that there is not only an idea of
beauty in your mind, but that there is such a thing as the one beauty
itself, of which your idea is a copy. This beauty exists outside the
mind, and it is something distinct from all beautiful objects.

What has been said of beauty may equally be said of justice, or of
goodness, or of whiteness, or of heaviness. There are many just acts,
but only one justice, since we use one word for it. This justice must
be a real thing, distinct from all particular just acts. Our ideas of
justice {186} are copies of it. So also there are many white objects,
but also the one whiteness.

Of the above examples, severa