I am now less sure than Sweetser that the external versions are 'root' meanings, and that the internal versions are constituted by metaphoric mappings. But this unfolding will suffice for our purpose. It allows us to present a view of the basic architecture of semantic domains. As subjects, we know that these domains require different attitudes of us, and that our focus will always be on one or another of the events occurring in all of them at the same time. We are embodied according to different basic dimensions of reality.
Temporal schemes distribute over the four basic domains.
People or persons are differently conceived of in different basic domains. These illustrations are only presented here as indications of the sort of cognitive grounding, and arguments in favour of it, that a theory of semantic domains has to take into consideration. A complete catalogue of available knowledge of this sort would include evidence from gestalt and developmental psychology, studies of language development, gesture, theory of mind, human evolution, and much more. This is not the place for a discussion of the technical details of the theory of mental spaces, but let us recall that blends are obtained by such spaces as structured inputs linked by mappings between two spaces. Direct mappings between more than two spaces would probably be chaotic.