By being happy, we sow anonymous benefits upon the world, which remain unknown even to ourselves, or when they are disclosed, surprise nobody so much as the benefactor.
心怀快乐时,我们便在世间播下无名的善意,连自己也未必察觉;即使后来被人提起,最惊讶的往往正是施予善意的人。
— Robert Louis Stevenson · Virginibus Puerisque, and Other Papers · An Apology for Idlers —