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 the naturalist or geographer of the supersensible regions, and draws their map; and, by acquainting us with new fields of activity, cools our affection for the old. These are at once accepted as the reality, of which the world we have conversed with is the show.