It takes more courage than we imagine to be perfectly simple with other men. Our frankness is often spoiled by a hidden barbarity, born of fear.No Man is an Island (New York: Harcourt Brace, 1955) pages 194-5
False sincerity has much to say, because it is afraid. True candor can afford to be silent. It does not need to face an anticipated attack. Anything it may have to defend can be defended with perfect simplicity.
-- Thomas Merton.
also in A Merton Reader, ed. by Thomas P. McDonnell, (New York: Image Books, 1989) page 123