Before he was Benedict XVI, Cardinal Joseph Ratzinger wrote what the Orthodox have quoted ever since — the “Ratzinger Formula.” In Principles of Catholic Theology (1987), reflecting on reunion, he proposed: “Rome must not require more from the East with respect to the doctrine of primacy than had been formulated and was lived in the first millennium.” From a future pope and the Church’s chief doctrinal officer, that is an extraordinary sentence.

He meant reunion as mutual recognition, not capitulation. In his own words, it could come if “the East would cease to oppose as heretical the developments” of the second millennium and recognize the Catholic Church as legitimate in the form she had grown into, “while… the West would recognize the Church of the East as orthodox and legitimate in the form she has always had.” The East is asked to grant legitimacy, not to adopt the Latin developments as its own. He set the whole proposal under an ancient image — Patriarch Athenagoras greeting the Pope as “the first among us in honour, he who presides in love.”

This is why the formula is genuinely conciliatory: first-millennium primacy, as the Orthodox read it, was honor and an appellate, coordinating role within a synodal Church — not the direct, immediate, universal jurisdiction defined in 1870. If Rome will take that as the measure of what it requires of the East, reunion stops looking impossible. John Paul II made the matching gesture in Ut Unum Sint (1995), inviting the Churches to help him find “a way of exercising the primacy which… is nonetheless open to a new situation” — though that invitation is the Pope’s, and the formula is Ratzinger’s, and the two should be kept distinct.

But honesty cuts both ways, and Ratzinger would insist on the limit himself. The formula is from a private theological work, not a magisterial act; it binds no one, and Rome has not rolled back Vatican I, which remains dogma. The concession is about the mode and exercise of the primacy — collegial, restrained, recognizable from the Fathers — and about what Rome may require of the East as the price of communion; it is not a surrender of the 1870 definitions. So the Orthodox rightly welcome the formula and rightly ask what it concretely changes. Read whole, it offers something real while refusing to overpromise: reunion need not mean the East becoming Latin — but it cannot mean Rome unsaying what it believes God has defined.