Josh McDermott teaches lecture seven of MIT's course 9.35, Perception, covering how the eye captures light and how the retina begins encoding it into neural signals. He walks through the anatomy of the eye, the optics that form an image on the retina, and the layered structure of retinal cells, including photoreceptors, bipolar cells, and ganglion cells. The lecture covers how rods and cones differ in their sensitivity and distribution across the retina, and how this arrangement shapes what the visual system can and cannot detect, from low light performance to acuity across the visual field. McDermott uses diagrams of retinal circuitry and cell types to explain how raw photon capture gets transformed into the first stages of a neural code before signals ever leave the eye. It is a foundational lecture for understanding everything later in the course about how the brain builds a visual world from this initial input.