Three economists redefined economic value the same year, unaware of each other

In 1871, William Stanley Jevons in England and Carl Menger in Austria independently argued that value comes from marginal utility — the satisfaction gained from one more unit — not the labour spent making a good. Léon Walras reached the same conclusion in Switzerland soon after. None had read the others' work; together their papers launched what's now called the marginalist revolution.

— William Stanley Jevons, The Theory of Political Economy — 1871; foundational text of the marginalist revolution
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