be-all and end-all

(not) the be-all and end-all

(Not) the most important event or thing. My little sister thinks that a date with the captain of the football team is just the be-all and end-all of her life right now. Oh honey, I know you're disappointed, but failing the driver's license test is not the be-all and end-all. You'll just practice some more and then take it again.
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Farlex Dictionary of Idioms.

be-all and end-all

Cliché something that is the very best or most important; something so good that it will end the search for something better. Finishing the building of his boat became the be-all and end-all of Roger's existence. Sally is the be-all and the end-all of Don's life.
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McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

be-all and end-all, the

The ultimate purpose, the most important concern. An early and famous use of this term is in Shakespeare’s Macbeth (1.6), in which the ambitious Macbeth soliloquizes about assassinating Duncan so as to become king: “. . . that but this blow [the murder] might be the be-all and the end-all here.” Eric Partridge held it was a cliché by the nineteenth century, but it is heard less often today.
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The Dictionary of Clichés by Christine Ammer
See also:
  • (not) the be-all and end-all
  • be-all and end-all, the
  • not the be-all and end-all
  • the be-all and end-all
  • end
  • think (someone) hung the moon and the stars
  • every horse thinks its own pack heaviest
  • a big head
  • back of (one's) mind
  • back of one's mind