 More broadly, there is the problem of just what experience can show. Can experience be a source of mathematical or logical knowledge? Can it reveal the causal relations that are traditionally regarded as the goal of science? Aristotle, as we saw, seems to have held that the mind has the power of identifying the causal powers that belong to particular kinds of entities. But it was never clear that experience alone could achieve such an insight. Medieval discussions of the “agent intellect” tended to regard it as an external power, or, at least, a human faculty that participates in a divine light. Thinkers such as Henry of Ghent went further, embracing the Augustinian idea that an act of divine illumination is required on each occasion we attain such insights. Under the impact of Aristotelian naturalism this idea was abandoned, but without (it must be said) any clear alternative.