Peter Saint-André has recently written this excellent article: The Art of Friendship

Here is an excerpt:

My attempt to do justice to the nature of friendship involves an implicit criticism, or at least modification, of the Aristotelian notion that "a friend is another self." . . . 

 

A friend is not literally another self, but one who shares many of my same interests, values, ideals, and perspectives. . . . 

 

There is a further implication of the fact that there is no such thing as another self: the falsity of the notion (which can be traced back to Aristotle) that a friend is a "mirror" who "reflects" my soul back to me. This idea, resurrected in recent times by psychologist Nathaniel Branden, contains a germ of truth but involves a metaphor that is so misleading as to be positively harmful. . . .