Who said "The most difficult thing is to be oneself."?

This quote is attributed to Marianne Moore.

The most difficult thing is to be oneself. - Marianne Moore

"The most difficult thing is to be oneself."

Marianne Moore

Poet American 1887–1972

"I like a long dress on a woman, I do not like to see a woman look like a man."

"The mind is an enchanting thing."

"Omit needless words."

"If you wish an interesting essay read all that the other side has to say."