
“Easy reading is damn hard writing.”
Also attributed to Ernest Hemingway and others; the earliest definite occurrence of this yet found in research for Wikiquote is by Maya Angelou, who stated it in Conversations With Maya Angelou (1989) edited by Jeffrey M. Elliot:
I think it's Alexander Pope who says, "Easy writing is damn hard reading," and vice versa, easy reading is damn hard writing
The statement she referred to is most probably:
You write with ease, to show your breeding,
But easy writing's curst hard reading
Clio's Protest, or the Picture Varnished (written 1771, published 1819) by Richard Brinsley Sheridan
Disputed