Welcome to Before the Microscope. I am Dalia Fouad, I am a historian of science in Alexandria, and this is a show about how people found things out before they had the tools we take for granted. We begin in Cairo around the year 1011, with a brilliant engineer who promised the caliph he could control the Nile, could not, and spent years confined to his house as a result. In that house, Ibn al-Haytham darkened a room, made a small hole in the shutter, and proved that light comes into the eye rather than shooting out of it. I will read his own description of the experiment, tell you which parts of his story are legend, and talk with a physicist about why his method still matters. You are listening on Witspeak Podcasts. Close the shutters.