With less silk, lace and gold than many of his predecessors displayed, Pope Francis on Tuesday was inaugurated at a Holy Mass in St. Peter's Square during which he appealed to world leaders to be protectors of the poor and the environment.

The Mass for the man born Jorge Mario Bergoglio was marked by a simplicity that contrasted with the former pope's 2005 inauguration.

In his homily, the pontiff offered a passionate pledge "to serve ‘the poorest, the weakest, the least important":

(The  pope, too) must open his arms to protect all of God's people and embrace with tender affection the whole of humanity, especially the poorest, the weakest, the least important, those whom Matthew lists in the final judgment on love: the hungry, the thirsty, the stranger, the naked, the sick and those in prison.

(READ more of the story from NPR)