This article explores lexical polysemy through an in-depth examination of the English preposition over. Working within a cognitive linguistic framework, the present study illustrates the nonarbitrary quality of the mental lexicon and the highly creative nature of the human conceptual system. The analysis takes the following as basic: (1) human conceptualization is the product of embodied experience, that is, the kinds of bodies and neural architecture humans have, in conjunction with the nature of the spatio-physical world humans inhabit, determine human conceptual structure, and (2) semantic structure derives from and reflects conceptual structure. As humans interact with the world, they perceive recurring spatial configurations that become represented in memory as abstract, imagistic conceptualizations. We posit that each preposition is represented by a primary meaning, which we term a PROTOSCENE. The protoscene, in turn, interacts with a highly constrained set of cognitive principles to derive a set of additional distinct senses, forming a motivated semantic network. Previous accounts have failed to develop adequate criteria to distinguish between coding in formal linguistic expression and the nature of conceptualization, which integrates linguistic prompts in a way that is maximally coherent with and contingent upon sentential context and real-world knowledge. To this end, we put forward a methodology for identifying the protoscene and for distinguishing among distinct senses.