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.