“Simplicity is the most difficult of all concepts.”
“To do nothing at all is the most difficult thing in the world, the most difficult and the most intellectual.”
“At times his arrogance did resolve itself into simplicity, though it was difficult, especially for strangers, to distinguish these occasions.”
“Writing is no trouble: you just jot down ideas as they occur to you. The jotting is simplicity itself--it is the occurring which is difficult.”
“To create a new belief is easy but to understand and improve someone's concept and to develop it for good is difficult.”
“...She had little patience with people who got intellectually lazy when faced with a difficult concept.”