But then by this time you will have comprehended that you cannot analyse concrete nature without abstracting.

Also I repeat, the abstractions of science are entities which are truly in nature, though they have no meaning in isolation from nature.
The character of the spatio-temporal structure of events can be fully expressed in terms of relations between these more abstract event-particles.

The advantage of dealing with event-particles is that though they are abstract and complex in respect to the finite events which we directly observe, they are simpler than finite events in respect to their mutual relations.

Accordingly they express for us the demands of an ideal accuracy, and of an ideal simplicity in the exposition of relations.

These event-particles are the ultimate elements of the four-dimensional space-time manifold which the theory of relativity presupposes.