What is an ‘Eternal Object’?

In the chapter titled ‘The Categorial Scheme’, Whitehead introduces a new distinction, doubtless the most important in Process and Reality as well as the most difficult to understand: actual entities are distinct from what he terms ‘eternal objects’:

the fundamental types of entities are actual entities, and eternal objects; and […] the other types of entities only express how all entities of the two fundamental types are in community with each other, in the actual world. (PR, 25)

This unequivocally expresses the importance of eternal objects. They are placed on the same plane as actual entities, with which they share a common characteristic of being the ‘fundamental types of entities’: ‘actual entities and eternal objects stand out with a certain extreme finality’ (PR, 22). We are now at a point where there can be no doubt as to the place occupied by actual entities in Process and Reality. They form the centrepiece of the entire speculative construction. When Whitehead writes in the preface that the ‘positive doctrine of these lectures is concerned with the becoming, the being, and the relatedness of “actual entities”’, it is now clear that he was literally expressing the project of the book. All of the elements set in place so far have concerned actual entities. These elements were entirely involved in the mode of existence and the emergence of actual entities.