Once, a chief told one of his servants to bring him the best meat from the market.
The servant brought him a tongue. The next day the chief told the servant to bring him the worst meat from the market.
The servant brought a tongue again. “What?” the chief said. “When I ask for the best meat, you bring a tongue and then you bring the same thing for the worst meat.”
The servant said, “Sometimes a man is very unhappy because of his tongue and sometimes his tongue makes him very happy.”
“You are right,” the chief said. “Let us be masters of our tongue!