Prepositions combine with nouns flexibly when describing concrete locative relations (e.g. "at/on/in" the school) but are rigidly prescribed when paired with abstract concepts (e.g. "at" risk; "on" Wednesday; "in" trouble). In the former case they do linguistic work based on their discrete semantic qualities, and in the latter they appear to serve a primarily grammatical function. We used the abstract concept of time as a test case to see if specific grammatically prescribed prepositions retain semantic content. Using ambiguous questions designed to interrogate one's meaningful representation of temporal relations, we found that the semantics of prescribed prepositions modulate how we think about time. Although prescribed preposition use is unlikely to be based on a core representational organization shared between space and time, results demonstrate that the semantics of particular locative prepositions do constrain how we think about paired temporal concepts. (Contains 3 figures and 1 table.)