A testing of oneself, a fear of giving in to the most banal and marketable of one’s talents, still draws many of the young to New York.That and, as always, the company of others fleeing something constricting where they came from.Together these young share a freedom, a community of inexpensive amusements, a casual living, and some rough times.It can’t be the living conditions that appeal, for only fond memory will forgive the inconvenience, risk, and squalor.Commercial Broadway may be inaccessible to them, but there is off- Broadway, and then off-off-Broadway.If painters disdain Madison Avenue’s plush art galleries, Madison Avenue dealers set up shop in the grubby precincts of Soho.But the purity of a bohemian dedication can be exaggerated.The artistic young inhabit the same Greenwich Village and its fringes in which the experimentalists in the arts lived during the Depression, united by a world against them.But the present generation is enough of a subculture to be a source of profitable boutiques and coffeehouses.And it is not all that estranged.Manhattan is an island cut off in most respects from mainland America, but in two areas it remains dominant. It is the banking and the communications headquarters for America.