The fifth-century Christological heresy that Christ's human nature was absorbed into His divine nature, so He effectively has one (mixed) nature rather than two distinct natures in one person. Named for Eutyches, an aged archimandrite of Constantinople who taught the position around 448 AD. Eutyches said that after the union, Christ had one nature — the divine having effectively swallowed up the human like a drop of vinegar in the ocean. The position is the opposite error to Nestorianism (which split Christ into two persons): where Nestorianism over-distinguishes, Eutychianism over-unifies. The Council of Chalcedon (451 AD) condemned both: Christ is one person in two natures, without confusion, without change, without division, without separation. The Chalcedonian definition has been the orthodox standard ever since. Eutychianism, in its modified form Monophysitism, survives in the Coptic, Ethiopian, Syrian, and Armenian Orthodox churches. The doctrinal point matters: if Christ's human nature was absorbed, He cannot fully represent humanity in His atoning work.