This lecture focuses on the scientific legacy of the Arab polymath Alhazen (Ibn al-Haytham; b. ca. 965 CE in Basra, d. ca. 1041 CE in Cairo). A special emphasis will be placed on his mathematical approaches to natural philosophy in the context of his studies in optics, and by way of his geometrization of the inquiries in classical physics and establishing the methodological rudiments of experimentation and controlled testing. To illustrate some of the principal aspects of his geometrical redefinition of the key concepts of natural philosophy qua physics, I shall consider the analytical case of his positing of place (al-makān) as a postulated geometric void in the context of his critical refutation of the definition of topos in Book IV of Aristotle’s Physics.