The leaders of the Byzantine delegation to Ferrara-Florence were the Emperor John and the Patriarch of Constantinople, Joseph. Joseph was a fervent supporter of reconciliation among the churches and full communion between them under the primacy of Rome. By the time of the Council, however, he was very old; two days after the council documents were signed, he passed away.
After Joseph died, Mark of Ephesus wrote his allies in Constantinople, stating his opinion that the Patriarch was not of sound mind at the time he signed the documents. His evidence for this -- and make what you will of it -- was that the teachings of the Council endorsed beliefs that Mark believed to be heresy. In Mark's opinion, Joseph would NEVER have signed them while in his right mind; since Joseph did endorse them, he MUST have been crazy, his enthusiastic participation in their formulation notwithstanding. (Unless, of course, the documents were forged . . . which is a whole 'nother argument that there isn't enough evidence to settle conclusively.) Additionally, Mark felt that the Latins had applied financial pressure to speed the negotiations along when the Pope refused to help pay for the upkeep of the many hundreds of servants the bishops had brought with them from Byzantium. This transformed the Council from an honest deliberation to an occasion of coercion. Consequently, he felt free to disregard the authority of Joseph, and reject the union that the Patriarch had made.
Now: if the Orthodox bishops had participated fully in the deliberations of the Council of Ferrara-Florence, and accepted its teachings, that would satisfy the requirements of an Ecumenical Council, the teaching of which would be binding on the faithful of all the rites and autocephalous churches of Christendom. (In Churchland, an Ecumenical Council is a VERY big deal.) On the basis of Mark's reports, however, the Greek bishops refused to accept Joseph's signature. Instead, they insisted on convening a synod of local bishops to review the documents, and consider the underlying issues
de novo.
Participation in the Council had always been controversial among the clergy; after suffering the predations of Italians for centuries, the populace were hostile from the outset. No Latin theologians were invited to the Greek synod to explain the basis for union. Furthermore, in the face of public pressure, some of the theologians who had endorsed the Council recanted, and testified that they had "sold out" their faith to get their hands on the Pope's money. At this point, Ferrara-Florence was a dead letter in Byzantium. The Paleologi hewed to the union until their city fell, but it never caught on with the people. After the Ottoman conquest, it was quickly repudiated as invalid; if anything, the Orthodox remember it as an example of Latin trickery.
Catholics, on the other hand, think the agreements were fairly obtained; they consider the Council to be binding. Nobody doubts St. Mark's personal holiness. Neither does anyone question the sincerity of his beliefs. All the same, on the liturgical calendar of the Latin rite, no day has been set aside to celebrate his feast.
