24 If anyone asks how it is that the statements of the council of Chalcedon are of such outstanding excellence in their clarity and their efficiency in the refutation of error, we reply that this arises from the fact that ambiguities had been removed and a most exact terminology was used. For in the Chalcedonian definition of the faith and the same concept underlies the terms 'Person' ( Prósopon ) and 'Hypostasis' ( Upóstasis ); the term 'Nature' has a totally different sense, and its meaning is never given to the other words. So that the Nestorians and Eutychians of old and certain modern writers err when they maintain that the council of Chalcedon corrected the decision of the council of Ephesus. Rather the one perfected the other, so that a synthesis or composition of the main Christological doctrine was available in fuller form for the second and third oecumenical councils of Constantinople.
Source: Sempiternus Rex Christus (Vatican.va)