 Already in the 1688 Entretiens sur la métaphysique, Malebranche had suggested that the union with God can be explicated in terms of a causal relation between God’s ideas and our mind. After 1695, he develops this suggestion by introducing the notion of “pure” or non-sensory intellectual perceptions that are produced by God’s efficacious idea of extension. Yet he also stresses in this later period that such an idea is the causal source of our sensations. One advantage of this extension of the doctrine of efficacious ideas to sensations is that it yields a fairly clear explanation of Malebranche’s claim to Arnauld that an idea is “intelligible extension rendered sensible by color or light.” Prior to 1695, Malebranche explained how intelligible extension is so rendered by appealing somewhat obscurely to the fact that the soul “attaches” colors to a non-sensory idea. However, the theory of efficacious ideas allowed him to say that this idea is rendered sensible by causing in us the appropriate sensations of color and light. The claim that we see ideas in God is thus transformed into the claim that our soul has intellectual and sensory perceptions that yield an understanding of the truth concerning bodies in virtue of their causal relation to God’s idea of extension. Drawing on Robinet’s results, one scholar has concluded that while Malebranche started with the vision in God, he ended with a vision by God (Alquié 1974, 209).