Medium of exchange was observed as early as Oresme, Copernicus and then in 1558 by Sir Thomas Gresham, that bad money drives out good in any marketplace (Gresham's Law states "Where legal tender laws exist, bad money drives out good money"). A more precise definition is this: "A currency that is artificially overvalued by law will drive out of circulation a currency that is artificially undervalued by that law." Gresham's law is therefore a specific application of the general law of price controls. A common explanation is that people will always keep the less adultered, less clipped, sweated, less filed, less trimmed coin,
Good Girl Gone Bad and the Universal Music Group respectively. "Good Girl Gone Bad" received generally favorable reviews from music critics. At Metacritic, which assigns a normalized rating out of 100 to reviews from mainstream critics, the album received an average score of 72 based on 17 reviews. "Uncut" called it a "shiny, trans-atlantic blend of Europop vim, R&B grit and Caribbean bounce." Andy Kellman of AllMusic deemed it quintessential pop music and said each of its tracks was a potential hit. Quentin B. Huff of PopMatters praised the album, describing it as "more raw, perhaps edgier and more risqué" than Rihanna's previous material.