When the satisfaction or the security of another person becomes as significant to one as is one’s own satisfaction or security, then the state of love exists. … under no other circumstances is a state of love present, regardless of the popular usage of the word.
— Harry Stack Sullivan, Conceptions of Modern Psychiatry: The First William Alanson White Memorial Lectures. New York; W. W. Norton & Company, 1966. pp. 42-43
— posted by Roger W. Smith