Ask the cashier, the bus driver, the barber what they’ve learned on the job. Everybody is an expert at something.

Any job done for years builds knowledge that exists nowhere in writing. A driver can read a street before anything happens on it, a barber knows how heads actually grow, somebody on a till can tell you more about how people behave than most books on the subject. It stays unmentioned because nobody asks, and because they do not file it under expertise.

Ask one person this week what they know now that they did not when they started. Pick a quiet moment rather than a queue. Listen for the specific detail rather than the general answer, since that is where the real knowledge shows.