A fortnight hence in the Vatican, 2,600 bishops of the Roman Catholic Church will meet in a gathering so rare that only 20 others like it have been convened in the 20 centuries of Christian history. The purpose of the Second Vatican Council is what Pope John XXIII calls an aggiornamento-a modernization. This self-reform will affect the way the church looks to other Christians. The Pope hopes that they will be favorably impressed, and that Catholicism may be pointed toward the far-distant goal of nearly all Christians: their ultimate unity in one church.