The greatest thing by far is to be a master of metaphor; it is the one thing that cannot be learned from others; and it is also a sign of genius, since a good metaphor implies an intuitive perception of the similarity of the dissimilar.
Men spoke much in my boyhood about restricted or ruined men of genius: and it was common to say that many a man was a Great Might-Have-Been. To me it's a more solid and startling fact that any man in the street is a Great Might-Not-Have-Been.