There is widespread disagreement as to exactly what Augustine might have meant by his theory of learning, in which Christ, the truth, teaches within. The precise interpretation of Augustine's doctrine of illumination has been the subject of centuries of debate. How is this kind of learning process which Augustine outlines—a process by which the word of God illumines the soul—to be understood? The major schools of thought on this subject have been: the ontologistic version, which regards the immediate presence of the divine light, the continuity between the mind of man and the mind of God, as primary in the act of learning; the ideogenetic version, which regards the activity of the word of God, mysteriously producing ideas in the human mind, as primary in the learning process; and, finally, what we might call the normative version, which understands the metaphor of illumination to refer to the way in which the divine light provides an ultimate standard of certainty by which knowledge is evaluated, rather than describing an inner, psychological process through which the act of learning occurs.