Malebranche on Sensory Cognition and "Seeing As"

Nicolas Malebranche famously holds that we see all things in the physical world by means of ideas in God. In some writings he seems to posit ideas of particular bodies in God, but when pressed by critics he insists that there is only one general idea of extension, which he calls "intelligible extension." But how can this general and "pure" idea represent particular sensible objects? I develop systematic solutions to this and two other putative difficulties with Malebranche's theory of sensory cognition by appealing to the notion of "seeing as" and to his doctrine that ideas in God have causal powers to affect the mind.