To send a letter from afar; to correspond with someone. This idiom refers to a legend about a wild goose carrying a message tied to its leg while the envoy [[苏武|蘇武|su1 wu3]] was held captive by the [[匈奴|匈奴|xiong1 nu2]].

a metaphor for the tragic scene of disaster victims or refugees crying out in hunger and distress or being left homeless