be-all and end-all, the

(not) the be-all and end-all

The most important event or thing. Often used in the negative. 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.
See also: and

be-all and end-all, the

The most important element or purpose, as in Buying a house became the be-all and end-all for the newlyweds. Shakespeare used this idiom in Macbeth (1:6), where Macbeth muses that "this blow might be the be-all and the end-all" for his replacing Duncan as king. [Late 1500s]
See also: and