Illumination

The most influential theories of illumination explain certain features of our knowledge by developing an analogy with ordinary sensory vision and the role played in it by light. According to theories of this sort, our knowledge of necessary and immutable objects and truths requires the activity of a kind of intelligible light illumining objects that are purely intelligible, thereby making them ‘visible’ to our mind. Plato held that this light comes from the Form of the Good, Augustine that it comes from God, and others that it is intrinsic to reason itself.

The peculiar nature and behaviour of light has provided a model not just for theories of knowledge but also for philosophical accounts of fundamental features of reality. Neoplatonist cosmologies, for example, liken the genesis of the universe to the emanation of rays of light from a light source. Theories of illumination therefore can be metaphysical as well as epistemological. Both kinds of theory have their historical roots in Platonism broadly construed.