This study establishes a relation between the semantics of the subject and the direct object-NP and aspect. The notion of event is central. Events have a beginning and an end. This means in temporal terms that events have a point in time at which they begin and a point in time at which they end. However, events are not defined in temporal terms but in spatial terms. This means that they are defined in terms of the entity that can be used to identify their beginning and the entity that can be used to identify their end. These two entitites are denoted by the subject and the direct object-NP respectively. The name of the event is provided by the verb. It is these three notions that make up Event Structure: the entity denoting the beginning, i.e. the object of origin; the entity denoting the end, i.e. the object of termination; and the event itself. The three primitives are independently motivated in the domain of tense interpretations of sentences. Their presence or absence affects these interpretations in a systematic way.