The human race has re?ected so long and often on these prob lems that the same patterns of thought recur in almost every age. We should know what these thoughts are. We should know what answers have been suggested by those who have most in?uenced ancient and modern thought. We shall want to do our own thinking and find our own answers. It is, however, neither necessary nor advisable to travel alone. Others have helped dispel the darkness, and the light they have kindled may also illumine our way.