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general::
Phrase(s): What must be, must be. [and] What(ever) will be, will be.
Prov. If something is fated to happen, you cannot stop it from happening.; You cannot foretell the future. • Harry hoped for many months that he would regain the use of his legs after the accident, but it soon became apparent that he would not. "What must be, must be," he thought resignedly. • I’d like to win the contest, but I can’t be sure that I will. What will be, will be. • The doctors have done all they can. Whatever will be, will be.
McGrawhill's American Idioms And Phrasal Verbs