Eric Osborn’s book presents a major study of Irenaeus (125-200), bishop of Lyons, who attacked Gnostic theosophy with positive ideas as well as negative critiques. Irenaeus’s combination of argument and imagery, logic and aesthetic, was directed to the bible. Dominated by a Socratic love of truth and a classical love of beauty, he was a founder of Western humanism. Erasmus, who edited the first printed edition of Irenaeus, praised him for his freshness and vigour. He is today valued for his splendid aphorisms, his optimism, love of the created world, evolutionary view of history, theology of beauty and humour. Why have two millennia of European culture been so creative? Irenaeus points to Greek ways of thinking and the Christian Bible. Irenaeus’s thought is complex, yet rewarding to the critical reader, and this full study of it will be of interest to theologians, historians of ideas, classicists, scientists and students.