This wonderful French phrase describes that incredibly annoying feeling of thinking up the best cutting putdown or the funniest reposte in answer to someone, five minutes too late! Literally meaning “staircase wit”, the phrase is thought to have been coined by the 18th century philosopher and wordsmith Denis Diderot, chief editor of the Encylopaedie. He found he could only think of the best responses after walking away from an argument down the stairs (escalier) on the way out.