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. The whole boundary of a finite event may be
looked on as a particular example of a vagrant solid as a locus. Its
particular property of being closed prevents it from being definable as
an abstractive element.

When a moment intersects an event, it also intersects the boundary of
that event. This locus, which is the portion of the boundary contained
in the moment, is the bounding surface of the corresponding volume of
that event contained in the moment. It is a two-dimensional locus.

The fact that every volume has a bounding surface is the origin of the
Dedekindian continuity of space.

Another event may be cut by the same moment in another volume and this
volume will also have its boundary. These two volumes in the
instantaneous space of one moment may mutually overlap in the familiar
way which I need not describe in detail and thus cut off portions from
each other's surfaces. These portions of surfaces are 'momental areas.'

It is unnecessary at this stage to enter into the complexity of a
definition of vagrant areas. Their definition is simple enough when the
four-dimensional manifold of event-particles has been more fully
explored as to its properties.

Momental areas can evidently be defined as abstractive elements by
exactly the same method as applied to solids. We have merely to
substitute 'area' for a 'solid' in the words of the definition already
given. Also, exactly as in the analogous case of a solid, what we
perceive as an approximation to our ideal of an area is a small event
far enough down towards the small end of one of the equal abstractive
sets which belongs to the area as an abstractive element.

Two momental areas lying in the same moment can cut each other in a
momental segment which is not necessarily rectilinear. Such a segment
can also be defined as an abstractive element. It is then called a
'momental route.' We will not delay over any general consideration of
these momental routes, nor is it important for us to proceed to the
still wider investiga