In On Truth Grosseteste presents an illuminationist theory of knowledge after outlining his theory of truth. Because created truth is a conformity between things and their eternal reasons, we can only know created truth if we know that a created thing conforms to its eternal reason in God. But as we can only see a body as colored if an external light is shed on its color, rendering it actually visible to us, so in order for us to see a created thing as true, an external light must be shed on its truth, rendering it actually visible to us. This truth is the adequation of the thing and its eternal reason in God’s mind, and thus an external light, the light of the Supreme Truth, God, must be shed on both the thing and its eternal reason if it is to be visible to the mind. Grosseteste hastens to point out that this doesn’t require that the knower see God himself or even be aware of God, for only the pure of heart see God as he is in himself in the face-to-face vision of God. All the same, all who know truth must in some way have at least an unwitting cognition of the Supreme Truth and its light, and in it a vision of the eternal reasons, that falls short of the direct vision of God.