Walt Whitman

Walter “Walt” Whitman (May 31, 1819 – March 26, 1892) was an American poet, essayist and journalist. Whitman is among the most influential poets in the American canon, often called the father of free verse. Born on Long Island, Whitman worked as a journalist, a teacher, a government clerk, and–in addition to publishing his poetry–was a volunteer nurse during the American Civil War. Whitman’s major work, Leaves of Grass, was first published in 1855 with his own money. The work is an American epic. He continued expanding and revising it until his death in 1892.

When shows break up what but One’s Self is sure?
What you are picks its way.
One’s Self I sing; a simple separate person.

Further Reading:
Emerson on Know Thyself
George Sand on Know Thyself
Montaigne on Know Thyself