Knowledge of Knowledge

On the one hand, it seems that if i know something, i should know that I know it. On the other hand, as socrates also points out, it's hard to see what good it does to know that i know If i know that two plus two equals four, that's good enough for all practical purposes. So we have something of a paradox: knowledge of knowledge is absolutely essential but knowledge of knowledge seems empty and useless. Once socrates and critias have banged their head against this problem for a while, the dialogue ends in a stale mate without any agreement as to what temperance, or for that matter, self, knowledge really is.