The evidential reading of German locative 'an'

German inferential perception verbs license an evidential reading of PPs headed by an: They refer to the information source of an inference and to directly perceived entities (Müller, 2020). This paper aims to show that this reading of 'an' is derivable from its basic locative meaning by compositional means. This is achieved by analyzing evidential 'an'PPs as event-internal modifiers in the framework of Two-level-semantics (Lang and Maienborn, 2019). Results of a corpus study show that evidential 'an'PPs refer to bearers of tropes which provide the contextually relevant information source and are perceivable on the bearer’s boundary surface. This is predicted by the locative meaning of 'an' as worked out in Carstensen’s (2000; 2015) cognitivist-attentional approach.