Who said "The difficult it is that does not tire."?

This quote is attributed to Marianne Moore.

The difficult it is that does not tire. - Marianne Moore

"The difficult it is that does not tire."

Marianne Moore Work

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."

"Hard work never killed anybody."

"Work with purpose and integrity."

"Hard work pays off in the end."

"A man's gotta do what a man's gotta do."