Sweetness returns after bitterness.

The Story of the Western Wing, a play by the Yuan-dynasty playwright Wang Shifu (c. 1260–1336), is counted among the four great classical dramas of China. In this tale of love between the poor scholar Zhang Sheng and the noblewoman Yingying, these four characters appear in the scene where the two are reunited after countless hardships — "苦盡甘來, 時來運轉" — when the bitter is exhausted the sweet arrives, and when the time comes fortune turns. The phrase later became a proverb across all of East Asia. Similar ideas existed before Wang Shifu. The Book of Changes offers "否極泰來" — when blockage (否) reaches its extreme, openness (泰) arrives — as a notable example. The Southern Song Chan monk Yefu Daochuan had already used the form "苦盡甜來" in his Commentary on the Diamond Sutra. But because Wang Shifu's play was popular theater, "gojingamnae" settled into the language of ordinary people through this work. What is striking is that these four characters are not a command to "endure," but a declarative statement that "this is certain to happen." The message to a person in suffering is delivered not in the language of will, but in the language of natural law.

The Latin verb resilire is made of two parts: re- (again) + salire (to leap, to jump). Literally, "to spring back, to rebound." The verb was originally used in ancient Rome to describe physical phenomena — a ball bouncing off a wall, a bowstring released and snapping back into place. The word was borrowed into English in the early 17th century. In its early form, "resiliency," Francis Bacon (1561–1626) used it in his 1625 essay "Of the Resiliency of the Air" as a physics term to explain the elasticity of air. In other words, resilience was, from the very start, not "the language of suffering" but "the language of elasticity." From the mid-19th century its meaning expanded. In the 1850s the British navy used "resilience" for the property of a ship's hull returning to its original shape after striking the waves. Then, in the mid-20th century, psychologists began to apply the word to the human interior. The decisive moment came in the 1970s, when Emmy Werner, in her longitudinal study of children on the Hawaiian island of Kauai, called those who recovered from adversity "resilient children." It was the moment a metaphor from physics became a core concept of human psychology.