Iranian people annually commemorate Sheikh Muslih od-Din Sadi Shirazi (C. 1213-1291), one of the greatest figures of classical Persian literature, on April 21, which has been named Sadi Day.
Following is Maxim 34 from Sadi’s Gulistan translated by Richard Francis Burton:
When a sage comes in contact with fools, he must not expect to be honored, and if an ignorant man overcomes a sage in an oratorical contest, it is no wonder, because even a stone breaks a jewel.
What wonder is there that the song
Of a nightingale ceases when imprisoned with a crow
Or that a virtuous man under the tyranny of vagabonds
Feels affliction in his heart and is irate.
Although a base stone may break a golden vase,
The price of the stone is not enhanced nor of the gold lost.