This monograph pursues a structural analogy between the availability of an existential interpretation in states and the telicity of events. Focusing on evidence from both verbal and adjectival predicates, it argues that quantization forms the basis of a unified theory of aktionsart and provides a theory in which the availability of an existential interpretation in states is, like the telicity of events, determined compositionally by the predicate and the quantization of its internal argument. Quantization is further argued to reflect the internal temporal constitution of the stages of an individual which is tied to the generation of an existential interpretation. This monograph will be of interest to syntacticians and semanticists who are specifically concerned with compositional approaches to eventualities, and to those who have a more general interest in the role linguistic theory can play in determining core properties of the mind.