This Working Group chapter extended the themes of "cultures of optical knowledge" and "perspective practices" to pre-Renaissance contexts, and conducts a microscopic study of early optics and perspective through a combination of written sources, primarily in Arabic and Persian. The focus was on the historical meanings and evolving contexts of key terms and concepts, starting with "optics" and "perspective" and their distinct and cross-genre representations in terms of both overlaps and divergences, with reference to an evolving Index Of Terms in Arabic (IOTA+). Close examinations suggest that the earlier, broader traditions of optics and perspective were much more closely related than the later, narrower, cases of optics proper and ideas of linear perspective. The central argument was that, while the closeness of the earlier traditions of optika, ikhtilāf al-manāẓir, and De aspectibus can be explained by the prominence of the subjects of sight and light, the divergence of the later traditions of manāẓir, perspectiva, and linear perspective is related to the transmission of one of the earliest sources associated with all these subjects: Euclid’s Optics. This is where the Greco-Arabic transmission of specific parts of the Euclidean text—the second definition and eighth proposition, associated with early optics and perspective—transforms critical terms and premises, respectively towards and away from concepts central to the development of Renaissance perspective.