Silence is the sanctuary of prudence.
There is none who cannot teach somebody something, and there is none so excellent but he is excelled.
Nothing is good for him for whom nothing is bad.
You have to appear wiser and more prudent than is required by the people you are dealing with if you want to give a high opinion of yourself.
Hear, see, and be silent.
The sage has one advantage: he is immortal. If this is not his century, many others will be.