In the theological skies of both the Greek and the Latin Church between the seventh and fourteenth centuries, usually known as the Middle Ages, a number of remarkable men appeared. They centered their lives in Christ and searched for an understanding of the faith which they shared and which their forebears had carefully explained over the first five centuries of Christianity. Yet in the process of trying to understand christian doctrine, the two great halves of Christendom grew apart. Differences in language and events led to differences of emphasis, teaching and practice, and sometimes to conflict.