In his 1526 essay Monetae Cudendae Ratio, Nicolaus Copernicus identifies currency debasement as a critical threat to states, alongside dissension, mortality, and barren soil, arguing that debased money covertly undermines economic stability by eroding trust in its value as a consistent measure for trade. He explains that money, typically gold or silver imprinted with a recognized symbol, loses value through excessive copper alloy, reduced weight, or wear, leading to inflation and trade disruptions, as seen in Prussia where coins shifted from high silver content to predominantly copper. Copernicus details Prussia’s historical monetary decline, particularly after the Battle of Tannenberg, where debased coins coexisted with better ones, causing confusion and economic harm, with modern Prussian coins containing far less silver than in earlier times. To address this, he proposes a unified minting system under royal oversight, issuing standardized coins with a fixed silver content (e.g., 20 marks per pound of silver), withdrawing old debased coins, and aligning Prussian currency with stable standards like the Polish groat to restore economic prosperity. He emphasizes that sound money fosters trade, craftsmanship, and abundance, warning that failure to reform risks Prussia’s economic collapse, with copper-heavy currency driving out gold and silver and stifling foreign trade.