Fixed the rules of the conclave, and made a reunion with the Greeks that their own Church never accepted.
- Where
- Lyons — Lyon, France
- Convoked by
- Pope Gregory X, by the bull Salvator noster of 31 March 1272
- Pope
- Gregory X, who had been elected after the longest conclave in history and legislated to make sure it never happened again
- Sat
- Opened 7 May 1274; six general sessions, closing 17 July
- Sessions
- Held in the cathedral of St. John at Lyons
- Bishops present
- About 300 bishops, 60 abbots and many more clergy, with King James I of Aragon in person and envoys of the Greek emperor and of the Mongol Ilkhan
What it faced
Gregory X had three aims: to reunite the Greek Church, to recover the Holy Land, and to reform the clergy. He also had a private grievance to legislate about. His own election had taken almost three years — the cardinals at Viterbo were eventually locked in, put on short rations and had the roof taken off the building before they chose him — and he had no intention of leaving his successors to the same farce.
The reunion was the emperor Michael VIII Palaeologus's project more than the Greek Church's. He had retaken Constantinople from the Latins in 1261 and now faced Charles of Anjou assembling an army to take it back with papal blessing. Union with Rome would remove the pretext. It was, on his side, a political necessity dressed as a theological agreement.
So the Greek delegation, arriving late in June after a shipwreck that drowned part of the embassy, came empowered to accept the Roman terms: the Filioque, the primacy, and the Latin doctrine of purgatory. They were not, however, empowered to make their Church believe any of it.
What it defined
- ✠That the Holy Spirit proceeds eternally from the Father and the Son — not as from two principles, but as from one principle.
- ✠The union of the Greek Church with the Latin, on the basis of the Greek acceptance of the Roman claims.
- ✠The law of the conclave: cardinals locked in, cut off from the world, and put on progressively shorter rations until they elect.
- ✠Reform of religious orders, restricting new foundations — the decree that nearly suppressed the Carmelites and Augustinians.
In its own words
“We profess faithfully and devotedly that the holy Spirit proceeds eternally from the Father and the Son, not as from two principles, but as from one principle.”
“…they shall all live in common in one room, with no partition or curtain… If, within three days, the cardinals have not provided the church with a pastor, they are to be content for the next five days with a single dish… after which they shall have only bread, wine and water until they do provide.”
Its constitutions
Law rather than doctrine — and one of them, the conclave, still governs how a pope is chosen.
- Const. 2The conclave: enclosure, no communication with the outside world, shrinking rations, and no revenues to the cardinals while the see is vacant.
- Const. 23Restricts new religious orders founded since Lateran IV; the Carmelites and Augustinian friars were allowed to continue provisionally, and survived.
- Const. 26–27Against usury: foreign moneylenders are to be expelled, and no community may let them rent premises.
- ✕It did not reunite the Churches. The Greek Church was never consulted and never consented. The bishops, monks and people of Constantinople rejected the union outright; the emperor imposed it by force and imprisoned opponents, and when he died in 1282 he was denied Christian burial by his own Church. His son Andronicus II repudiated the union at once.
- ✕It did not define purgatory for the first time. The profession of faith read on behalf of the Greek emperor treats of purification after death, and it is the first conciliar statement of the sort, but the doctrine has older roots and its full definition comes at Florence and Trent.
- ✕It did not recover the Holy Land. Acre, the last mainland crusader city, fell seventeen years later.
What people think it did
The Orthodox rejected the union of Lyons out of mere nationalism, having agreed to it in council.
What happened: There was no Greek council. The emperor sent a delegation empowered to accept Roman terms because he needed Western political protection, and the Greek Church was not asked. Opposition came from the monks, the bishops and the ordinary faithful — Michael VIII resorted to imprisonment and mutilation to enforce it. Whatever one thinks of the theology, treating this as a Church's considered acceptance is not accurate.
What followed
The conclave is the one lasting achievement. Everything about a modern papal election — the enclosure, the secrecy, the exclusion of outside communication — comes from this constitution, and it was written by a man who had waited nearly three years to be elected.
Two of the greatest theologians of the age were bound up with this council and neither saw it finish. Thomas Aquinas died on the journey to it, at Fossanova in March 1274. Bonaventure took a leading part in the reunion negotiations, and died in July while the council was still sitting.
The reunion's failure taught a lesson the next attempt did not learn: an agreement signed by an emperor and a delegation is not an agreement made by a Church. Florence would repeat the experiment in 1439 and get the same answer.
Follow it further
Sources
Every date, figure and quotation on this page was checked against the conciliar text or a published translation before it was written, and independently re-checked by three separate passes over dates, quotations and theology. Where the sources disagree — attendance figures above all — the page gives the range rather than choosing.