Protagoras and Meno.

[Edit: sorry all, but the last summary was really lame. Admins, please use something better - here's my best shot.]

Protagoras and Socrates discuss the unity and teachability of virtue. Along the way, we get conversations about poetry and sophism, and a healthy dose of hedonism. This is an early Platonic dialogue; read it for fun, but don't be afraid to laugh!