and pains present and future? These propositions to us have an appearance
of paradox--they are really moments or aspects of the truth by the help of
which we pass from the old conventional morality to a higher conception of
virtue and knowledge. That virtue cannot be taught is a paradox of the
same sort as the profession of Socrates 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