Final answer:
Louis IX prohibited nobles from minting their own money to centralize economic control, increase royal revenues, and consolidate authority within the monarchy, thus strengthening the French absolute monarchy.
Step-by-step explanation:
Louis IX made it illegal for nobles to mint their own money mainly to consolidate economic power and control over the kingdom of France. By centralizing the minting process, the monarch asserted greater control over economic activities, including the circulation and the value of money. In doing so, Louis IX combated the chaos of various nobles creating their own currencies, which could have led to inconsistencies in coinage, undermining the stability of the economy.
Additionally, controlling the minting of money was a way to increase royal revenues and assert the monarch's power over the nobles. It was a step towards centralizing authority and reducing the power of nobles, who could potentially use their resources and influence to challenge the king. By having sole control over the issuance of currency, the monarch also aimed to prevent financial abuses and corruption that could occur if too many entities had the right to produce money.
Centralization of currency was a common step toward strengthening the absolute monarchy as evidenced in the policies of later rulers like Louis XIV, which included establishing royal manufacturing, promoting French manufacturing, and instituting tariffs on foreign goods to bolster the economy and the power of the monarchy.