  Yet William realizes that such statements may give an incorrect impression of his thought. Thus, at one point in On the Universe he writes that “every substance includes, if it is proper to say so (si dici fas est), the creator's essence within itself” (OO I, 920b), and he goes on to note that it is difficult to state clearly the sense in which the creator is in creatures. In other passages he emphasizes God's transcendence of creatures: “the first being (esse) is for all things the being (esse) by which they are … It is one essence, pure, solitary, separate from and unmixed with all things.” Often he appeals to an analogy with light: the first being fills “all things like light cast over the universe.  By this filling or outpouring it makes all things reflect it. This is their being (esse), namely to reflect it” (Switalski 1976, 45; Teske and Wade 1989, 89). William perhaps intends in such remarks to exploit the medieval view that a point of light (lux) and the light emitted from that point (lumen), though distinct, nonetheless are also in some deep sense the same.