This essay examines the rhetorical and visual practices Juan Valverde implemented in his anatomical treatise Historia de la composici.n del cuerpo humano, which I argue aided in sharpening his readers’ observational skills while concurrently making use of collaborative techniques between artists, engravers, and printers in early modern publishing houses. Valverde cultivated his readers’ observational abilities by imploring them to look closely and make comparisons between his images, Vesalius’s woodcuts in De humani corporis fabrica, and, if possible, an anatomized corpse. This constituted an alternative empirical practice, expanding the existing program for anatomical inquiry to include a close visual analysis of the existing corpus of images, a task that marked him for criticism by Vesalius, but also promoted diligent observations from his readers. Although both anatomists made competing claims as to the validity of their anatomical accuracy, Valverde intentionally enlisted his readers to become adjudicators between the two sets of printed images.