  The final rationalistic aspect of Malebranche’s thought that deserves attention here is his theory of causation. For Malebranche, a cause is that between which and whose effect there is a necessary connection. On his view, the causal connection that is characterized by this kind of necessity is that between God’s will and its effects. Thus, for Malebranche, only God has causal efficacy. What we take to be real causes—for example the motion of a billiard ball that collides with another that then begins to move—are in fact only occasional causes, the occasions for the operation of the only real cause.