Tiruvalluvar

“ Are men who can't their lore acquired to other's ears expound.
Those who are unable to set forth their acquirements (before others) are like flowers blossoming in a cluster and yet without fragrance. ”

“ A tongue that rightly speaks the right is greatest gain,
It stands alone midst goodly things that men obtain.
The possession of that goodness which is called the goodness of speech is (even to others) better than any other goodness. ”