One of the most remarkable things about the life of Paul is how little we really know about him and how little he tells us about his life. How is it possible for a man so little given to self-confession to emerge as such a distinct and clear person from his letters and to convey such an intense personal identity to us? This is a curious phenomenon, especially when we recall the passionate soliloquies of a Jeremiah—in many ways Paul’s prophetic models—or a Marcus Aurelius’s Meditations, or even the Confessions of Augustine, for whom psychological autobiography is the point of departure for speculative thought. We tend to forget that Paul gives only hints about his external career and internal religious reflections. And so we ignore not only the occasional character of his letters but also the incidental nature of his self-preoccupation.
Paul the Apostle: The Triumph of God in Life and Thought, 3.