The mind that builds software is far smaller than the software it builds, and almost everything good in engineering is a way of living with that gap. 3 February 2026 cross-cutting You've probably heard that the mind can hold seven things at once. It's the most repeated figure in popular psychology, and the man who came up with it didn't actually believe it. George Miller called his 1956 paper "The Magical Number Seven, Plus or Minus Two" half as a joke. He wrote that the way the number kept showing up across experiments that had nothing to do with each other was probably just a coincidence, and at one point he said he felt persecuted by an integer. He was right to be suspicious. Later researchers stripped away the little tricks we use to cheat - rehearsing under your breath, grouping digits into chunks - and the number fell. When you take all that away, the honest figure for how many separate things a person can hold in mind at once, with no help at all, is about four. Four.…