I remember reading something like this in Marx's first volume of Capital, where he was explaining how the labour is "self-expanding", that is, producing more than it costs to sustain (except he used work-hours in accounting). Funnily enough, if you read Marx's account closely enough, there is no unfairness in payment: what's bought is "ability to work", its marginal price in the competitive market is exactly the cost of living, and the fact that the price of the resulting product the higher is irrelevant.