think that something of the kind is true.' And in the Meno, after dwelling
upon the immortality of the soul, he adds, 'Of some things which I have
said I am not altogether confident' (compare Apology; Gorgias). From this
class of uncertainties he exempts the difference between truth and
appearance, of which he is absolutely convinced.

In the Republic the ideas are spoken of in two ways, which though not
contradictory are different. In the tenth book they are represented as the
genera or general ideas under which individuals having a common name are
contained. For example, there is the bed which the carpenter makes, the
picture of the bed which is drawn by the painter, the bed existing in
nature of which God is the author. Of the latter all visible beds are only
the shadows or reflections. This and similar illustrations or explanations
are put forth, not for their own sake, or as an exposition of Plato's
theory of ideas, but with a view of showing that poetry and the mimetic
arts are concerned with an inferior part of the soul and a lower kind of
knowledge. On the other hand, in the 6th and 7th books of the Republic we
reach the highest and most perfect conception, which Plato is able to
attain, of the nature of knowledge. The ideas are now finally seen to be
one as well as many, causes as well as ideas, and to have a unity which is
the idea of good and the cause of all the rest. They seem, however, to
have lost their first aspect of universals under which individuals are
contained, and to have been converted into forms of another kind, which are
inconsistently regarded from the one side as images or ideals of justice,
temperance, holiness and the like; from the other as hypotheses, or
mathematical truths or principles.

In the Timaeus, which in the series of Plato's works immediately follows
the Republic, though probably written some time afterwards, no mention
occurs of the doctrine of ideas. Geometrical forms and arithmetical ratios