Any ambitious painter faces a conundrum: what can a painting say today that hasn’t already been said? Some artists, chastened by the historical record, may phrase it a little differently: how to paint something worth hanging on a wall, when the walls of our museums already boast the most extraordinary paintings? Leland Bell (1922-1991), who would have turned one hundred years old this fall, was possessed by the second of these challenges. His centennial show at the New York Studio School, which includes some two dozen paintings and drawings selected by curator Steven Harvey, puts on full, luminous display his passions, insights and struggles.