Looking back upon the formative centuries of Christianity and Judaism, we focus on how insiders thought about themselves by what they said concerning “others.” The reason is that, from the perspective of our day, the critical issue of world civilization, the principal and generative tension in the life of humanity, emerges from that protean concern: who am I? who is the one different from me? who are we? who are those different from us? We take the measure of me the matter by its capacity to come to full expression in nearly every dimension of society and culture, politics and collective existence, and religion. The theory of the other expresses the sense of self. The lines of structure mark out, to begin with, an insider from an outsider. From parturition to death, the individual takes shape through successive separations and unions. From the center to the frontier, societies discover themselves by signifying differences and stipulating what difference makes. So, in all, in the heart and center of the study of humanity we take up the divided heart, the uncertain vision, the on-center perspective, that, in the eye of the beholder, tells a person who is like, and who is unlike.