Pope Benedict XVI shocked the world Monday with his announcement that he would become the first pontiff since 1415 to resign. Yet it's to his credit that the pope chose to step down at age 85 rather than remain in power while his health -- and perhaps his service to the church he has ministered to so ably -- declines.

In the words of Cardinal Timothy Dolan of New York, the pope has brought to every task "the tender heart of a pastor" and "the incisive mind of a scholar."

In his eight-year papacy, Benedict has spoken strongly about the church's mission to the poor -- of all faiths.

He has urged global negotiators to find an agreement on climate change that represents the needs of impoverished populations and future generations.

At the same time, the pope has maintained a tight -- and for some, a too-tight -- focus on orthodoxy and preserving church traditions.

Last summer, for example, the Vatican accused a group of American nuns of straying from church doctrine and spending too much time on social justice issues.

Still, Pope Benedict has been diligent about remaining accessible to as many people as possible -- whether leading the community in prayer at Yankee Stadium or at St. Patrick's Cathedral, or, as Dolan noted yesterday, "in a stirring, private meeting in Washington," where he felt pain and "brought a listening heart to victims of sexual abuse by clerics."

Pope Benedict has been passionate about broadening the church's message.

His latest foray into this area was the launch of his Twitter account (@pontifex). It's aimed at reaching the world's 1.1 billion Roman Catholics and anyone else who might be interested.

So far, he's attracted 1.5 million Twitter followers -- not too shabby for a neophyte.

He could have some sway over the appointment of his successor given that he has named a majority of the voting-age members of the College of Cardinals.

Benedict XVI has been a complex and intellectual pontiff, and his successor needs to build on what he did, just as Benedict himself continued the work of John Paul II. The outreach and the dialogue with the world must continue as courageously as it has under Pope Benedict XVI, who kept the faith.