It is related that Mahmud of Ghazna was once walking in his garden when he stumbled over a blind dervish sleeping beside a bush.
As soon as he awoke, the dervish cried, “You clumsy oaf! Have you no eyes, that you must trample upon the sons of men?”
Mahmud’s companion, who was one of his courtiers, shouted, “Your blindness is equaled only by your stupidity! Since you cannot see, you should be doubly careful of whom you are accusing of heedlessness.”
“If by that you mean”, said the dervish, “that I should not criticize a sultan, it is you who should realize your shallowness.”
Mahmud was impressed that the blind man knew that he was in the presence of the king, and he said mildly, “Why, O dervish, should a king have to listen to vituperation from you?”
“Precisely”, said the dervish, “because it is the shielding of people of any category from criticism appropriate to them which is responsible for their downfall. It is the burnished metal which shines most brightly, the knife struck with the whetstone which cuts best, and the exercised arm which can lift the weight.”
Hmm…the shielding of someone from criticism appropriate to him can lead to his downfall…