Conceived originally as a serious presentation of the development of philosophy for Catholic seminary students, Frederick Copleston's nine-volume A History Of Philosophy has journeyed far beyond the modest purpose of its author to universal acclaim as the best history of philosophy in English. Copleston, an Oxford Jesuit of immense erudition who once tangled with A. J. Ayer in a fabled debate about the existence of God and the possibility of metaphysics,...