The Chalcedonian Definition: one person in two natures

The council convened by Emperor Marcian at Chalcedon in 451 deposed Dioscorus and Eutyches, restored the Antiochenes condemned in 449 and approved Cyril's letters and Leo's Tome. The Definition confesses one and the same Christ, perfect in Godhead and in humanity, of a rational soul and body, consubstantial with the Father in Godhead and with us in humanity, like us in all things except sin; born of Mary the Theotokos, acknowledged "in two natures without confusion, without change, without division, without separation", the properties of each being preserved and coming together in one Person and one Hypostasis. At Rome's insistence it says "in two natures" rather than "from two natures". According to Pelikan, the Definition was composed of ready-made elements: Cyril's letters, the formula of 433, Leo's Tome and an expression of Theodoret.