University of Pennsylvania Libraries, Lawrence J. Schoenberg Collection, MS LJS 429, is a small booklet containing materials of natural philosophy, chiefly related to the effects of cosmic forces on human biology. Two of its diagrams illustrate the mentalizing process of the Aristotelian-Thomist psychology anima sensitiva, or the process through which sensory experience is formed as a mental perception. This essay points out the ways in which these diagrams differ from a standard (Thomist) medieval model of Mind. During the very late Middle Ages, the analysis of Mind as anima sensitiva and mens appears to shift from being action-based (analysed in terms of abilities and powers) to being substantive-based (analysed in terms of substantial agents using material tools). I will suggest that these two diagrams unusually model “faculty psychology” in a way that seems to foreshadow one we associate more with the time of Descartes, and even of Locke and Hume.