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Keep your sense of humor and people will sympathize with you, as in She's always cheerful and has dozens of friends; laugh and the world laughs with you. This expression actually is part of an ancient Latin saying that concludes, weep and the world weeps with you. The current version, with the ending weep and you weep alone (meaning "you'll get no sympathy in your sorrow"), first appeared in 1883 in Ella Wilcox's poem "Solitude." O. Henry used a slightly different version: "Laugh, and the world laughs with you; weep, and they give you the laugh" (The Count and the Wedding Guest, 1907).
American Heritage Idioms
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Phrase(s): Laugh and the world laughs with you; weep and you weep alone.
Prov.When you are happy, people will want to be around you and share your happiness, but when you are sad, people will avoid you. • Nancy: When Harry and I were dating, all our friends invited us places and called to say hello. Now that we’ve broken up, they treat me as if I don’t exist. Jane: Laugh and the world laughs with you; weep and you weep alone.
McGrawhill's American Idioms And Phrasal Verbs