Master has an apprentice who often complains. One day, Master put a handful of salt into a glass of water and let the apprentice to  drink.

The apprentice said: ” Salty to bitter.”

Master sprinkled more salt into the lake, letting the apprentice to taste the lake again.

After drinking, the apprentice said: “Pure and sweet.”

Master said: “The pain in life is salt, and its saltiness or lightness depends on the container that holds it.”