 We cannot give further details here, but refer the interested reader to Thomason (1986) who discusses how to construct time as a continuum—isomorphic to the real numbers—and uses a different construction originally proposed by Walker (1947). Empirical evidence for events being ontological primitives will be presented in  section 8 where we review psychological studies on event perception. We will now move to lexical and grammatical aspect, that is the expression of event types and how a given event is conceptualized, which form basic concepts in linguistic theory.