I will call this abstractive element the solid as an abstractive element, and I will call the aggregate of event-particles the solid as a locus.
The instantaneous volumes in instantaneous space which are the ideals of our sense-perception are volumes as abstractive elements.

What we really perceive with all our efforts after exactness are small events far enough down some abstractive set belonging to the volume as an abstractive element.
It is difficult to know how far we approximate to any perception of vagrant solids.

We certainly do not think that we make any such approximation.

But then our thoughts--in the case of people who do think about such topics--are so much under the control of the materialistic theory of nature that they hardly count for evidence.

If Einstein's theory of gravitation has any truth in it, vagrant solids are of great importance in science.