In a homily preached on 18 July 2021 at the Monastère Saint-Benoît, liturgical scholar Dom Alcuin Reid offers both a reflection on the place of the traditional Latin Mass in the unity of the Church, and a description of how his monastery will respond to Francis's Traditionis Custodes. He asked us to highlight his call to offer a votive Masses pro Ecclesiæ unitate.Readers will have seen his two articles taken from our archives: What Benedict XVI thought about liturgical change from 2005 and Summorum Pontificum a restoration from 2007.   Our Holy Father Pope Francis has, last Friday, enacted legislation in respect of the usus antiquior of the Roman rite — the more ancient form of the liturgy — in the light of his grave concerns that its celebration has endangered the unity of the Church and fostered division within it, including a rejection of the legitimacy of the Second Vatican Council and of the Magisterium of the popes following it. These are grave concerns, and any pope is right to address them when he believes they exist. The service of the unity of the Church is one of the particular duties of the Petrine ministry for which each pope must answer before Almighty God on the day of judgement. It is beholden to us, therefore, as faithful Catholics, to take his concerns very seriously indeed.