One Person's Gain, Another's Loss — The Essays of Montaigne

Montaigne opens with Demades the Athenian condemning a man who sold funeral necessities for excessive profit, arguing that such gain requires many deaths. Drawing on Seneca, Montaigne calls that verdict ill grounded. If we punish one trade for living off misfortune, we must punish every kind of gain, since no profit is made except at another's expense.

He then piles examples across the economy. Merchants need youth's excess, farmers need dear grain, architects need ruined buildings, lawyers need quarrels, and even clergy depend on death and vice. An ancient comic says physicians prefer friends sick and soldiers prefer war. The sharper turn is inward: examine your own heart and you will find private hopes rising at a neighbour's cost.

Montaigne closes by comparing this to nature's rule that one thing's growth consumes another, quoting Lucretius on transformation as the death of what came before. His aim is not cynicism but clear sight about mutual dependence.