Take The Wind Out Of Someone's Sails Meaning

(idiomatic) To discourage someone greatly; to cause someone to lose hope or the will to continue; to thwart someone.

Example: c. 1860, Louisa May Alcott, "Aunt Kipp":
  "I tell you Van Bahr Lamb is a fool." . . .
  But Polly . . . completely took the wind out of her sails, by coolly remarking,— "I like fools."
1922, Frances Hodgson Burnett, The Head of the House of Coombe, ch. 31:
  Could he have some elderly idea of wanting a youngster for a wife? Occasionally an old chap did. Serve him right if some young chap took the wind out of his sails.
1990 May 27, Serge Schmemann, "German rightist quits after party suffers setback," New York Times (retrieved 17 July 2011):
  [T]he Republicans . . . have been repeatedly battered in the polls since German unification became a mainstream German concern and took the wind out of their sails.
2011 April 14, "Quotes of the Day," Time:
  "It took the wind out of our sails," he says. "I had no Plan B. I was a wreck."