The Great FiresBy: Jack Gilbert JOYCE'S MOTTO has had much fame but few apostles. Among them, there has been Jack Gilbert and his orthodoxy, a strictness that has required of this poet, now in the seventh decade of his severe life, the penalty of his having had almost no fame at all. In an era that puts before the artist so many sleek and official temptations, keeping unflinchingly to a code of "silence, exile, and cunning" could not have been managed without a show