Most formal semantic accounts of evidentiality focus on propositional eviden- tiality [PE], i.e. where an evidential scopes over a proposition, and can have DIRECT flavor (sen- sory perception) or INDIRECT flavors (inference, hearsay, etc). In this work, we venture into the sparsely studied domain of nominal/non-propositional evidentiality [NPE] (e.g. (1)), where an evidential scopes over a nominal. A striking fact about NPE systems is that the only available flavor of evidence is overwhelmingly DIRECT (Jacques 2018, Aikhenvald 2018). Why does such a fundamental divide exist among languages with PE and NPE? More succinctly, what is it about nominals that favors only sensory perception? In this work, we provide the first compar- ative formal semantic account (to our knowledge) of perception of nominals and propositions that tackles these questions, and adds another dimension: temporality. We first discuss how per- ception is intertwined with tense in NPE, and vital contrasts with tense in PE perception. Then we present an analysis couched in modal logic (Hughes and Cresswell 1986, a.o.), where at the semantic core of DIRECT evidentiality are spatio-temporal accessibility relations that are grounded in historical necessity, deriving perception in NPE & PE systems in a principled way.