Not to converse with a man worthy of conversation is to waste the man. To converse with a man not worthy of conversation is to waste words. The wise waste neither men nor words.
The silent treasuring up of knowledge; learning without satiety; and instructing others without being wearied: which one of these things belongs to me?
Therefore only through education does one come to be dissatisfied with his own knowledge, and only through teaching others does one come to realize the uncomfortable inadequacy of his knowledge. Being dissatisfied with his own knowledge, one then realizes that the trouble lies with himself, and realizing the uncomfortable inadequacy of his knowledger.
When a man's knowledge is sufficient to attain, and his virtue is not sufficient to enable him to hold, whatever he may have gained, he will lose again.