Since writing his biography with the bold title of The Great Reformer, the one question I get most asked is: "What is Pope Francis actually changing?" The answer is both nothing and everything. His reforms represent a genuine shift, but not as the world knows it or would like it to be.

Yes, he is shaking things up. He is bold and brave. He takes on vested interests and is unafraid to court unpopularity (which only makes him more popular). The papacy has become the engine of change, rather than the lid on it. Theologians once cold-shouldered are supplying some of the big thinking of Francis' teaching. Tough pastoral issues that were never allowed into the open - chief among them the plight of the divorced and remarried who wish to return to parish life - are now at the heart of discussions in the synod of bishops.

Francis has looked to big names in the accountancy and management worlds to modernize Vatican finances and communications. He has appointed clergy sex-abuse victims to a high-level commission reforming the church's safeguarding policies. And in a huge range of little decisions - the simplicity of his dress, the guesthouse and canteen where he sleeps and eats, his disarming directness and frankness in interviews - he is transforming the institution of the papacy itself, triggering a "revolution of normalcy."

But it all has a precedent in the Second Vatican Council in the 1960s. It was the council that called for a church of and for the poor, that sought to purge the church of outdated legalism and monarchic elements, and that called for a more "pastoral" church, one focused on the needs of the poor and excluded. The Francis papacy is, essentially, picking up where the council left off - especially in the unfinished business of church governance, where Francis has been quietly leading what may turn out to be his key reform.

This was the council's unfinished business. While it endorsed the principle that the bishops were co-governors, always "with and under the pope," the idea was never followed through. Rome continued to act as if it were the head office of an absolute monarch, with the world's dioceses its branches. It is how many Catholics to this day think of the church, which is why some of them are upset at Francis' changes.

Referring to himself on the night of his election as the bishop of Rome who "presides in charity" over the world's dioceses, Pope Francis sent a signal as clear as white smoke that he would implement collegiality. He has done so quietly, but firmly, in three main ways.

First, he named senior archbishops from all the continents to be his advisers, and to reform the Vatican bureaucracy. Because these archbishops do not live in Rome but in their dioceses, he is essentially putting the local church in charge of changing the Vatican.

Second, he has restored the old idea of the College of Cardinals - senior bishops whose main role is to elect the pope - as a kind of senate, one that sits over two days each year to deliberate on some major issue facing the church. (Because most cardinals are also heads of dioceses, this, too, is a major transfer of authority.)

Lastly, Francis has reformed the synod of bishops. It is no longer merely a talking shop, summoned and controlled by the Vatican, but has become a body with real power to deliberate on major issues facing the church. The pope still makes the ultimate decisions; but having told the synod to debate fearlessly, and to wrestle over 18 months with, sensitive pastoral issues such as the place of the divorced in parish life, he can hardly ignore its conclusions.

Yet there are clear boundaries to all these changes. Francis takes broad soundings, but he is the one who decides. The synod may debate pastoral challenges posed by gay couples or the divorced, but it is taken for granted that marriage is between a man and a woman, open to children, and for life. And while the collegiality reforms are of huge historical significance, they involve restoring something lost, not introducing something new.

And that, in a nutshell, is why Francis is a true Catholic radical.

Asked by a journalist in 2014 if he was a revolutionary, he did not protest, but said a true revolutionary was "one who goes to the roots" - the true meaning of radical, but hardly Che Guevara. He also said that authentic change was about strengthening identity, not replacing it. For Francis, following the theologian Yves Congar, true reform begins on the periphery - think of Jesus starting out in Galilee, among the fisher folk and shepherds - and happens when the center opens up to that pressure. The Francis reform is all about bringing that pressure to bear on power: reconnecting the center to the periphery, Rome to the local church, the powerful to the powerless.

Consider his itinerary in the United States. He comes to Washington from Havana, and goes straight from Congress to be with homeless folk. From the United Nations and Ground Zero he makes his way to Harlem, to be with immigrant kids. And after addressing bishops in St. Charles Borromeo Seminary in Wynnewood, he goes to be with those locked up in Curran-Fromhold. This pope always goes out to the margins, and speaks from there.

Francis' reform is not about making the church more acceptable to modern society, but about enabling the church better to evangelize it. Above all, it is about freeing the church to meet the needs of ordinary people to be in relationship with God. That is why, as progressive as he may be on ecology or market capitalism, he is no liberal. He does not question or dilute Catholic teaching, but wants to make it easier to live out. Almost everything he does puts ordinary people first, and risks offending the elites. That, too, makes him a radical in the Catholic tradition: He is wresting control of the church from the princes, and giving it back to ordinary people, putting them first.

The pope's announcement Tuesday that he will give all priests the power to forgive abortion was typical. There wasn't a lot new in it, theologically or legally, and what there was left church lawyers scratching their heads. But it gave a simple, Christ-like message, seeing a woman who chooses an abortion as firstly a victim, and inviting her to be set free by God's forgiveness.

He was clearing the path to God, making it easier to access the healing of mercy. And here we reach the heart of his reform. Convinced that conversion happens when we directly experience that merciful love, whether through charity, forgiveness, or concern for the poor, Francis wants the church to put that mercy front and center of its offer to humanity. Is this radical, new, or revolutionary? Was Jesus?

Austen Ivereigh is the author of "The Great Reformer: Francis and the Making of a Radical Pope" (Picador).