ER Season 1 Episode 19

Carol: It's darkest before dawn.
This is a reference to the proverb "The darkest hour is just before the dawn." Thomas Fuller, the English theologian and historian, may have been the first person to commit this notion to print; his religious travelogue A Pisgah-Sight Of Palestine And The Confines Thereof (1650) contains the line "It is always darkest just before the Day dawneth." Many, many authors and poets since have incorporated a version of the adage into their writings.