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.
"Genius is divine perseverance." Divine patience I believe he originally used, perseverance is better in my opinion. Genius I cannot claim nor even extra brightness but perseverance all can have.