For example, when we know that there is a blazing fire (_i.e._ material and scientific objects undergoing various exciting adventures amid events) and opposite to it a mirror (which is another material object) and the positions of a man's face and eyes gazing into the mirror, we know that he can perceive the redness of the flame situated in an event behind the mirror--thus, to a large extent, the appearance of sense-objects is conditioned by the adventures of material objects.

The analysis of these adventures makes us aware of another character of events, namely their characters as fields of activity which determine the subsequent events to which they will pass on the objects situated in them.

We express these fields of activity in terms of gravitational, electromagnetic, or chemical forces and attractions.

But the exact expression of the nature of these fields of activity forces us intellectually to acknowledge a less obvious type of objects as situated in events.

I mean molecules and electrons.