Harnack’s classic study of the relationship between history and Christianity asks the difficult question of just how much Christianity relies on historical veracity for its basis. His approach to this question incorporates the concept of personality and how it relates to an understanding of history. Boldly addressing the objections that history is tied to development or principle, Harnack argues that the personality of Jesus, thus Christianity, survives despite the necessity of historical criticism. The impact of Harnack’s logic during the period of the first quest for the historical Jesus would be hard to exaggerate.