Ralph Waldo Emerson describes a true friend as a person with whom I can think aloud. This absence of the need to put on a façade is an essential and foundational aspect of all genuine friendships. He goes on,
I am arrived at last in the presence of a man so real and equal, that I may drop even those undermost garments of dissimulation (concealing your true thoughts), courtesy, and second thought, which men never put off, and may deal with him with the simplicity and wholeness with which one chemical atom meets another.
Essays, First Series