At Ferrara and Florence, Western intellectuals met with the greatest Greek scholarly and theological delegation that ever came to Latin soil. The Greeks did not come empty-handed. They brought with them de luxe editions of Greek sacred and, above all, secular authors—coveted treasures for Renaissance Italians. To judge by the letters in which Ambrogio Traversari announced the arrival of the Greeks, Christian Humanists were as much interested in the codices of Plato, Plutarch, Euclid and Ptolemy, brought by the Emperor and Bessarion, as in the cause which brought the Greeks to Italy.

For the medieval world the Council of Florence provided the last great opportunity to close the gap separating Eastern from Western Christendom. Not only was it the most brilliant convocation of Greeks and Latins in the entire Middle Ages, but it marked the first occasion in centuries that East and West assembled in ecumenical council to debate the differences separating their two churches.

As the Council of Florence concluded its deliberations, the Greek Orthodox participants had a number of choices open to them. The Byzantine metropolitan and newly created cardinal of the Roman Church, Bessarion, elected to remain in the Roman West where his intellect and knowledge were so well appreciated, after a short visit to a Constantinople unreconciled to the idea of Union. The Metropolitan of all Russia, Isidore, likewise adorned with the red hat and invested by the Pope with legatine power over Russia, chose another solution. Proud Greek that he was, Isidore trusted his superiority over the Russians and decided to return to his see, bringing with himself the new faith. According to the Tale of Isidore's Council by the monk Simeon of Suzdal', the metropolitan explained to Pope Eugene IV the reasons for his confidence that Moscow would accept the Union: “They are all in my hands, all the princes and bishops,” Isidore told the Pope; “Not one of them dares argue with me; the Grand Prince is young and is under my will… their bishops are ignorant and they, too, fear me.”