(11) Finally, there is a subset of validities called
manifolds
. A manifold is itself a validity and is generally made up of smaller validities that together provide a
complete
account of the flow of spiritual power within some slice of reality. Consider, for example, the rules of Euclidean geometry. They're simple; most of us learn them in high school, if not sooner; and with them we can understand all the possible figures and transformations that can occur in flat space. Manifolds are the most sophisticated voidal media and determine whole domains of spiritual activity.
(12) I want to clarify - the void isn't all about math, but I've used mathematical examples because they're abstract, empty of content, just like the void. In mathematics, it doesn't matter what two things you add to what three other things; for as long as the things are distinguishable, you have five things. Likewise, regardless of what spirit affects you, if it acts through a validity then it directs your attention to a consequence.
(13) To return to the image of spirits as bearers of light, imagine the void as a prism through which the light of spirits is refracted. It has an infinite number of facets; it occupies no space but is present everywhere; it is the collection of all intelligible forms, and through some of these the light from every spirit must pass. Therefore, we can call the void the medium in which all spirits work and through which all reality is understood. And we can call each of its facets a 'voidal medium,' and many of them together 'voidal media.'