  Following Lawvere's description of metric spaces using enriched category
theory, we introduce a change in the base of enrichment that allows description
of some aspects of (relativistic) causal spaces. All such spaces are Cauchy
complete, in the sense of enriched category theory. Furthermore, we give
sufficient conditions on a base monoidal category for which enriched categories
are Cauchy complete if and only if their underlying categories are (their
idempotent arrows split).
