In this brief introduction to the life and works of this important leader of the early church, we gain a more accurate picture of the circumstances and pressures which were brought to bear on his pontificate. A brief introduction surveys the scanty sources which document Leo’s early life, and sets his pontificate in its historical context, as the Western Roman Empire went into serious decline, and Rome lost its former status as the western capital. Annotated translations of various excerpts of Leo’s letters and homilies are organised around four themes dealing with specific aspects of Leo’s activity as bishop of Rome: Taking each of these key elements of Leo’s pontifical activities into account, we gain a more balanced picture of the context and contribution of his best-known writings on Christology. This volume offers an affordable introduction to the subject for both teachers and students of ancient and medieval Christianity.