The essay analyzes the formation of the oft-cited trope of the image engraved (or painted) in the heart, topical in the Sicilian lyric of the thirteenth century, and the ways in which it re-discusses a painstaking issue of Aristotelian physiology. The trope of the “pintura nel core” (figure in the heart), as described in Giacomo da Lentini's Meravigliosa⋅mente and Madonna mia, a voi mando, is immediately assimilated to the faculty of memory, and the human ability to represent external reality by means of signa. This process of formation that happens in the heart and allows the poet to fall in love is reworked in the image of the “pintura” carved like a seal into wax. The lexical choices of Giacomo's poems point to an Aristotelian understanding of sense perception, centered around the key role of the heart, dependent upon the fluidity of its bodily part, and resulting in an internal representation of phenomenal reality. The link between love lyric poetry and physiological learning shows the interdependence of these two fields of medieval culture, and the ways in which a debated scientific issue can be illuminated by the comparative analysis of vernacular literature and philosophical investigation. Giacomo's reworking of these Aristotelian physiological tenets testifies to his poetical ability to engage with medicine and aesthetic representation.