The other "revolutionary" Pope of 2013.

John Allen writes:

Equally notable is the way he's handled his departure. In his final address to the cardinals Feb. 28, Benedict pledged "unconditional reverence and obedience" to his successor, and he's held up his end of the deal. Other than a private letter he sent to an Italian atheist that was leaked by the recipient, Benedict has only been seen or heard in public when Francis has come calling or invited him to something.

Despite well-documented umbrage among some about the new direction under Francis, Benedict has done nothing to encourage a "loyal opposition" or to legitimize dissent from the new regime.

In effect, Benedict has gone from infallibility to near-invisibility, and entirely by his own choice. If that's not a "miracle of humility in an era of vanity," to invoke Elton John's Vanity Fair tribute to Francis back in June, it's hard to know what would be.

At a substantive level, several of the reforms for which Francis is drawing credit, including his cleanup of Vatican finances and his commitment to "zero tolerance" on sex abuse, amount to continuations of policies that began under Benedict.

Even if that weren't the case, the point remains that the "Francis effect" might have been lost to history without Benedict taking a step no pope had taken in 600 years -- and given the markedly different circumstances, one could argue it's a step no pope had ever taken in quite this way.

No question about it, Francis is shaking up the Catholic church and offering it a new lease on life. For the record, however, he wasn't the only maverick, the only revolutionary pope, of 2013.