Ask an economist to price a favour and you will get a number: the time it cost, the alternative use of that time, perhaps a discount for the warm glow. Ask the person who did the favour and you will get a look. The two answers are not in conflict. They are measuring different things, and the second is the one that compounds.
Kindness is expensive in the moment and cheap over a life. The moment is where the spreadsheet lives, and so the spreadsheet is forever advising against it: do not lend the ladder, do not cover the shift, do not write the reference. Follow the advice consistently and you arrive, decades later, with an unblemished ledger and no one to call.
What the round trip is worth
The experimental evidence is unusually consistent. People who give more, in money or time, report higher wellbeing, and the effect survives the obvious objections about who chooses to give. Societies with more everyday trust run cheaper: fewer contracts, fewer locks, shorter queues at the returns desk. None of this shows up in any single transaction, which is precisely why the single transaction is the wrong unit of analysis.
So the price of being kind is real, and it is worth paying. Not because virtue is its own reward — that is a consolation, not an argument — but because the returns arrive in a currency the spreadsheet does not accept, and the exchange rate, over a lifetime, is absurdly favourable.
