Between about 1910 and 1939, no one in the theater made a move without consulting George Jean Nathan. In the midst of scriveners, hacks and stringers, Nathan was the real thing: an erudite theater critic with more than 20 books to his credit, a fabled association with H.L. Mencken behind him (they co-edited "the Smart Set") and a range of European-bred tastes that gave him a sophistication that few of his colleagues could rival. He not only promoted the early Eugene O'Neill, but was a close friend of the playwright's and his staunchest champion. He elucidated G.B. Shaw for the masses and created the appetite that eventually established Sean O'Casey.