William Shakespeare coined a number of phrases that we still use today, including (in varying forms) the following from Twelfth Night.

 

“If music be the food of love, play on.”
— Duke Orsino 1.1.1

“My purpose is, indeed a horse of that colour.”
— Maria 2.3.148

“I am all the daughters of my father’s house and all the brothers too.”
— Viola 2.4.118

“Still you keep o’ th’ windy side of law; good.”
— Fabian 2.4.147 

“Be not afraid of greatness. Some are born great, some achieve greatness, and some have greatness thrust upon ’em.”
— Malvolio 2.5.128

“Why, this is very midsummer madness.”
— Olivia 3.4.50