But whether your Needle change or be permanent, all you mean by stating that it is situated on the Charing Cross Embankment, is that amid the structure of events you know of a certain continuous limited stream of events, such that any chunk of that stream, during any hour, or any day, or any second, has the character of being the situation of Cleopatra's Needle.
Finally, we come to the third statement, 'There are dark lines in the Solar Spectrum.' This is a law of nature.

But what does that mean?
It means merely this.

If any event has the character of being an exhibition of the solar spectrum under certain assigned circumstances, it will also have the character of exhibiting dark lines in that spectrum.
This long discussion brings us to the final conclusion that the concrete facts of nature are events exhibiting a certain structure in their mutual relations and certain characters of their own.

The aim of science is to express the relations between their characters in terms of the mutual structural relations between the events thus characterised.

The mutual structural relations between events are both spatial and temporal.