“To do nothing at all is the most difficult thing in the world, the most difficult and the most intellectual.”
“People are the most difficult thing in the world to change”
“The most difficult thing in the world is to know how to do a thing and to watch someone else do it wrong without comment.”
“The most difficult thing about Time, I have learned, is doing it.”
“[...] things most people do naturally are often inexplicably difficult for me.”
“One of the most difficult things in the world is to convince a woman that even a bargain costs money.”