On this day in 1791, in Newington Butts, south London, a blacksmith's family welcomed a boy named Michael Faraday. He was apprenticed to a bookbinder at fourteen, which turned out to be the best scientific education going, because he read the books before he stitched them shut.

Here is the one thing he found that still runs your house. Take a coil of wire and a magnet. Hold the magnet still inside the coil and nothing happens at all. Move it, and a current flows. It is the moving that matters, not the magnet. Think of a garden hose: water only goes anywhere if there is a difference in pressure between the two ends. Leave the taps equal and the hose just lies there in the grass, smug and empty. A stationary magnet is an equal-pressure hose. Wobble it, and you have made a difference, and the electrons shuffle along. Every power station on earth is a very expensive way of waggling magnets past wire.

What I love is the bookkeeping. Faraday numbered the paragraphs in his laboratory notebook, year after year, including the days when the needle stubbornly refused to twitch. He kept the failures where he could find them again. In my own lab days I mostly kept my failures in a drawer, so I salute him. The portrait below has him seated with his hands folded, quite calm, and a red wire looping off the table beside him, as if he had just put it down for a moment.