In this volume, Christoph Markschies presents a collection of papers on Origen, the Christian theologian from Alexandria (died approx. 254 AD), who is regarded as the first Christian thinker to work in a rigorous and systematic philosophical manner. The papers in the volume treat philological problems presented by Origen's texts, examine theological ideas he developed, and consider the parts played by Eusebius, the Church historian, and Ambrosius, Bishop of Milan, who as two key theologians from the fourth century continued the traditions established by Origen in both East and West.