The 80-year-old Pontiff is planning a purification of the Roman liturgy in which decades of trendy innovations will be swept away. This recovery of the sacred is intended to draw Catholics closer to the Orthodox and ultimately to heal the 1,000 year Great Schism. But it is also designed to attract vast numbers of conservative Anglicans, who will be offered the protection of the Holy Father if they covert en masse.
The liberal cardinals don't like the sound of it at all.
Ever since the shock of Benedict's election, they have been waiting for him to show his hand. Now that he has, the resistance has begun in earnest - and the Archbishop of Westminster, Cardinal Cormac Murphy-O'Connor, is in the thick of it.
"Pope Benedict is isolated," I was told when I visited Rome last week. "So many people, even in the Vatican, oppose him, and he feels the strain immensely." Yet he is ploughing ahead. He reminds me of another conservative revolutionary, Margaret Thatcher, who waited a couple of years before taking on the Cabinet "wets" sabotaging her reforms.
Benedict's pontificate moved into a new phase on July 7, with the publication of his apostolic letter Summorum Pontificum.
With a stroke of his pen, the Pope restored the traditional Latin Mass - in effect banned for 40 years - to parity with the modern liturgy. Shortly afterwards, he replaced Archbishop Piero Marini, the papal Master of Ceremonies who turned many of John Paul II's Masses into politically correct carnivals.
Cardinal Murphy-O'Connor was most displeased. Last week, he hit back with a "commentary" on Summorum Pontificum.
According to Murphy-O'Connor, the ruling leaves the power of local bishops untouched. In fact, it removes the bishops' power to block the ancient liturgy. In other words, the cardinal - who tried to stop Benedict issuing the ruling - is misrepresenting its contents.
Alas, he is not alone: dozens of bishops in Britain, Europe and America have tried the same trick.
Murphy-O'Connor's "commentary" was modelled on equally dire "guidelines" written by Bishop Arthur Roche of Leeds with the apparent purpose of discouraging the faithful from exercising their new rights.
A few years ago the ploy might have worked. But news travels fast in the traditionalist blogosphere, and these tactics have been brought to the attention of papal advisers.
This month, Archbishop Malcolm Ranjith, a senior Vatican official close to Benedict, declared that "bishops and even cardinals" who misrepresented Summorum Pontificum were "in rebellion against the Pope".
Ranjith is tipped to become the next Prefect of the Congregation for Divine Worship, in charge of regulating worldwide liturgy. That makes sense: if Benedict is moving into a higher gear, then he needs street fighters in high office.
He may also have to reform an entire department, the Pontifical Council for Promoting Christian Unity, which spends most of its time promoting the sort of ecumenical waffle that Benedict abhors.
This is a sensitive moment. Last month, the bishops of the Traditional Anglican Communion, a network of 400,000 breakaway Anglo-Catholics based mainly in America and the Commonwealth, wrote to Rome asking for "full, corporate, sacramental union".
Their letter was drafted with the help of the Vatican. Benedict is overseeing the negotiations. Unlike John Paul II, he admires the Anglo-Catholic tradition. He is thinking of making special pastoral arrangements for Anglican converts walking away from the car wreck of the Anglican Communion.
This would mean that they could worship together, free from bullying by local bishops who dislike the newcomers' conservatism and would rather "dialogue" with Anglicans than receive them into the Church.
The liberation of the Latin liturgy, the rapprochement with Eastern Orthodoxy, the absorption of former Anglicans - all these ambitions reflect Benedict's conviction that the Catholic Church must rediscover the liturgical treasure of Christian history to perform its most important task: worshipping God.
This conviction is shared by growing numbers of young Catholics, but not by the church politicians who have dominated the hierarchies of Europe for too long.
By failing to welcome the latest papal initiatives - or even to display any interest in them, beyond the narrow question of how their power is affected - the bishops of England and Wales have confirmed Benedict's low opinion of them.
Now he should replace them. If the Catholic reformation is to start anywhere, it might as well be here.