Courage
Courage is a virtue that Greek consider indispensible for the life. Socrates taught people that courage is the knowledge of good and evil generally, after diferentiating it from military courage and animal’s ignorant act of violence.(Plato, Laches, or Courage)
However, it could be the reverse. The knowledge of good and evil might only be aquired through courage. Wittgenstein, a legendary figure in philosophy, once tried to write a confession, though he’s not a Catholic or Protestant. He insisted his friends read it. Rush Rhees commented that Wittgenstein thought he had been performing for himslef in a character that was not genuine. His self-deception was not because his lack of wisdom, but lack of the will.He could not become clear by intellectual examination and argument with himself, but only by doing something he found diffficult, something that needed courage–such as writing out a confession to show his friends; or by doing something which brought him troubles which he hoped would do him some good; or in the war by trying to be placed in situations where his life was constantly in danger. (Rush Rhees, Postscript)
One issue that Wittgenstein has challenged Plato is whether the knowledge brings with virtue. Modern philosophers have found the seperation of knowledge and life. Or to put it in another way, knowledge in the modern society has left life alone.