rates that he knew
nothing. Plato means to say that virtue is not brought to a man, but
must be drawn out of him; and cannot be taught by rhetorical discourses
or citations from the poets. The second question, whether the virtues
are one or many, though at first sight distinct, is really a part of
the same subject; for if the virtues are to be taught, they must be
reducible to a common principle; and this common principle is found to
be knowledge. Here, as Aristotle remarks, Socrates and Plato outstep the
truth--they make a part of virtue into the whole. Further, the nature
of this knowledge, which is assumed to be a knowledge of pleasures and
pains, appears to us too superficial and at variance with the spirit
of Plato himself. Yet, in this, Plato is only following the historical
Socrates as he is depicted to us in Xenophon's Memorabilia. Like
Socrates, he finds on the surface of human life one common bond by which
the virtues are united,--their tendency to produce happiness,--though
such a principle is afterwards repudiated by him.

It remains to be considered in what relation the Protagoras stands to
the other Dialogues of Plato. That it is one of the earlier or purely
Socratic works--perhaps the last, as it is certainly the greatest of
them--is indicated by the absence of any allusion to the doctrine of
reminiscence; and also by the different attitude assumed towards the
teaching and persons of the Sophists in some of the later Dialogues. The
Charmides, Laches, Lysis, all touch on the question of the relation of
knowledge to virtue, and may be regarded, if not as preliminary studies
or sketches of the more important work, at any rate as closely connected
with it. The Io and the lesser Hippias contain discussions of the Poets,
which offer a parallel to the ironical criticism of Simonides, and are
conceived in a similar spirit. The affinity of the Protagoras to
the Meno is more doubtful. For there, although the same question is
discussed, 'whether virtue can be taught,' and the relation of Meno to
the Sophists is much the same as that of Hippocrates, the answer to the
question is supplied out of the doctrine of ideas; the real Socrates is
already passing into the Platonic one. At a later stage of the Platonic
philosophy we shall find that both the paradox and the solution of it
appear to have been retracted. The Phaedo, the Gorgias, and the Philebus
offer further corrections of the teaching of the Protagoras; in all of