This dissertation is a study of visuality in fourteenth-century Swabian Dominican Henry Suso’s works. It explores the novel intersection of literary hagiographical discourses, scientific visuality discourses, and negative theological discourses, from late antique Greece to medieval Middle East, Spain, and Central Europe, culminating in Suso’s Middle High German works. Suso was rare among monks in that he wrote quasi-autobiographically in addition to more standard theological tracts. Previous scholars discussing Suso productively analyzed his use of devotional images, but they have failed to note the impact of the scientific understanding of vision in his works. The scientific component came to the Central Europe through Paris, where Franciscan scholars like Roger Bacon were reading, synthesizing, and adapting then cutting-edge Middle Eastern physiology as part of their natural philosophy. The most revolutionary tract on vision was Ibn al-Haytham's Optics, who pioneered central tenets of the modern scientific method and unified three disparate schools of thought on vision into one revolutionary theory of vision, which is reflected in Suso’s texts. Images emanate out of their originals and physically touch the eye. Suso believed that both the external eye and the internal mind's eye were malleable, taking the shape of the image they perceived. This influenced his concept of human identity, because he felt that the entire human body was spiritually malleable, and could be literally reshaped by religious discipline. For Suso, when one views depictions of Christ and imitates Christ's Passion, the internal mental image of Christ can reshape their body and soul to be a mirror image of the suffering Jesus. This builds on the negative theological tradition—Christ, as imago Dei, is the medium by which one can “see” the infinite apophatic divine, which itself cannot be captured by any image or name. As the medium, Christ is in unmediated contact with the original divine from which he springs forth. Suso intends for his readers to become image of Christ, literally, and so he presents his works as an exemplar, a “true image” of how to do so, interweaving narrative, theological, and visual media to push the readers to grasp something unrepresentable.