Pope Leo, at his public audience today, offers a concise explanation of why Church leaders, the Roman Pontiff included, are not free to alter the faith. Their role, he explains— citing Vatican II— is to preserve the deposit of the faith. And:

• “Deposit” is a term that, in its original meaning, is juridical in nature and imposes on the depositary the duty to preserve the content, which in this case is the faith, and to transmit it intact.