I recall hearing in a Sociology course about a form of existentialism so dark that some people never accept they were alive until the moment of death itself. For most of us, even the slightest touch confirms what I'll jokingly call "our suspicion" that we actually exist. A handshake, pat on the back, or a hug can provide powerful validation. It's a mistake to take such an obvious thing for granted.
Different Drummer: Leo Buscaglia