Events are the things related by the relation of extension.

If an event A extends over an event B, then B is 'part of' A, and A is a 'whole' of which B is a part.

Whole and part are invariably used in these lectures in this definite sense.

It follows that in reference to this relation any two events A and B may have any one of four relations to each other, namely (i) A may extend over B, or (ii) B may extend over A, or (iii) A and B may both extend over some third event C, but neither over the other, or (iv) A and B may be entirely separate.

These alternatives can obviously be illustrated by Euler's diagrams as they appear in logical textbooks.
The continuity of nature is the continuity of events.