The sharp, seamless, full-colour picture you seem to be looking at right now isn't a direct recording of the world — it's a construction, built by your brain from a stream of messy and genuinely incomplete signals. This episode follows light on its journey from the cornea to the visual cortex, covering rods and cones, the blind spot, three-channel colour vision, and why optical illusions count as scientific evidence rather than mere party tricks.

You'll come away understanding how the eye focuses light onto the retina, why rods and cones divide labour between night vision and colour vision, what causes the blind spot and why you never notice it, how just three types of cone can produce a near-limitless range of perceived colour, why illusions reveal the assumptions the brain relies on to fill in gaps, and what's actually going wrong in shor ...