"Of at least equal importance with his entertainer’s cap was the jester’s function as adviser and critic. This is what distinguishes him from a pure entertainer who would juggle batons, swallow swords, or strum on a lute or a clown who would play the fool simply to amuse people. The jester everywhere employed the same techniques to carry out this delicate role, and it would take an obtuse king or emperor not to realize what he was driving at, since "other court functionaries cooked up the king’s facts for him before delivery; the jester delivered them raw."
It is in the nature of jesters to speak their minds when the mood takes them, regardless of the consequences. They are neither calculating nor circumspect, and this may account for the “foolishness” often ascribed to them. Jesters are also generally of inferior social and political status and are rarely in a position (and rarely inclined) to pose a power threat. They have little to gain by caution and little to lose by candor—apart from liberty, livelihood, and occasionally even life, which hardly seems to have been a deterrent. They are peripheral to the game of politics, and this can reassure a king that their words are unlikely to be geared to their own advancement. Jesters are not noted for flattery or fawning. The ruler can be isolated from his courtiers and ministers, who might conspire against him. The jester too can be an isolated and peripheral figure somehow detached from the intrigues of the court, and this enables him to act as a kind of confidant.
The jester also had humor at his disposal. He could soften the blow of a critical comment in a way that prevented a dignified personage from losing face. Humor is the great defuser of tense situations.”