“Leonard Riggio is the rich person who made Dia:Beacon possible. A demanding, emotional, self-made man — a Brooklyn cabbie’s son who built Barnes & Noble into the dominant bookseller in America — Riggio was the chairman of the Dia board during the years Dia:Beacon was being built. He believed in it with every fiber of his being. When Dia needed a piece of art to round out its permanent collection, he bought it. When cost overruns occurred, he covered them. But last year, Riggio abruptly, and angrily, resigned as Dia’s chairman.”