For millenia it was a goal of princes and alchemists to produce the Philosopher's Stone, a device by which common metals could be transmuted into gold. To modern people who know about economics, it seems a waste of time -- though gold does have some intrinsic use, most of its value is due to its scarcity and use as a means of exchange. If some medieval genius somehow did contrive to make such a Stone, it would give far less wealth to its creator than might be naively expected, because prices would soon rise to match the increased supply of specie. People with savings would also be ruined by the inflation.
However, I understand that this conception of money and value is quite new in historical terms, and was not commonly known in ages past. People knew that debasing coinage led to inflation, but that isn't quite the same as this, since someone might still naively think that a pure gold coinage would retain its value forever. Who was the first person to point out to the alchemists this specific aspect of their folly?