Central banks have changed how they manage money, using new methods that were once thought risky. The IMF and the BIS had different views on this change, but it turned out to be successful. By expanding money supplies and making new rules, central banks helped the economy and controlled financial risks. Now, central banks have more tools to keep the economy stable. Looking ahead, if big debts and rules fail, central banks may need to act. The big question is whether governments will let them.