The _Meno_ is a rediscussion on Platonic principles of the problem of the _Protagoras_: can virtue be taught? Meno, a general in the army of the famous Ten Thousand, attempts a definition of virtue itself, the principle that underlies specific kinds of virtues such as justice. After a cross-examination he confesses his helplessness in a famous simile: Socrates is like the torpedo-fish which benumbs all who touch it. Then the real business begins. How do we learn anything at all? Socrates says by Reminiscence, for the soul lived once in the presence of the ideal world; when it enters the flesh it loses its knowledge, but gradually regains it. This theory he dramatically illustrates by calling in a slave whom he proves by means of a diagram to know something of geometry, though he never learned it. Thus the great lesson of life is to practise the search for knowledge--and if virtue is knowledge it will be teachable. But the puzzle is, who are the teachers? Not the sophists, a discredited class, nor the statesmen, who cannot teach their sons to follow them. Virtue then, not being teachable, is probably not the result of knowledge, but is imparted to men by a Divine Dispensation, just as poetry is. But the origin of virtue will always be mysterious till its nature is discovered beyond doubt. So Plato once more declares his dissatisfaction with a Socratic tenet which identified virtue with knowledge. The _Phaedo_ describes Socrates' discussion of the immortality of the soul on his last day on earth. Reminiscence of Ideas proves pre-existence, as in the _Meno_; the Ideas are similarly used to prove a continued existence after death, for the soul has in it an immortal principle which is the exact contrary of mortality; the Idea of Death cannot exist in a thing whose central Idea is life. Such in brief is Socrates' proof. To us it is singularly unconvincing, as it looks like a begging of the whole question. Yet Plato argues in his technical language as most men do concerning this all-important and difficult question. That which contains within itself the notion of immortality would seem to be too noble to have been created merely to die. The very presence of a desire to realise eternal truth is a strong presumption that there must be something to correspond with it. The most interesting portion of this well-known dialogue is that which teaches that life is really an exercise for death. All the base and low desires which haunt us should be gradually eliminated and replaced by a longing for better things. The true philosopher at any rate so trains himself that when his hour comes he greets death with a smile, the life on earth having lost its attractions.