In his first major speech on the subject, Francis demanded Wednesday that financial and political leaders reform the global financial system to make it more ethical and concerned for the common good. He said: "Money has to serve, not to rule!"

It's a message Francis delivered on many occasions when he was archbishop of Buenos Aires, and it's one that was frequently stressed by retired Pope Benedict XVI.

Francis, who has made clear the poor are his priority, made the comments as he greeted his first group of new ambassadors accredited to the Holy See.