the mode of presentational immediacy. We may say that the brain has a material and a mental aspect, all three being abstractions from their indefinitely many constitutive occasions of experience, which are actual entities.

Inherent in each actual entity is its respective dimension of time. Potentially, each occasion of experience is causally consequential on every other occasion of experience that precedes it in time, and has as its causal consequences every other occasion of experience that follows; thus it has been said that Whitehead's