the flower of
the flower of (something)
The finest, most vital, or most exemplary part of something. Though many worry the legislation will hamper trade with foreign countries, I'm hopeful that it will help nurture and cultivate the flower of local industries. The community has been struggling to come to terms with the death of the three boys, all struck down in the flower of youth.
the flower of —the finest individuals out of a number of people or things.
Middle and early modern English did not recognize the modern distinction in spelling and sense between flower and flour , and the earliest instances of this expression relate to the sense that in modern English would be spelt flour , referring to the finest part of the wheat.
1991 Pat Robertson New World Order This vainglorious conqueror wasted the flower of French youth on his own personal dreams of empire.