How did the Council of Ephesus describe the union of the Word and human flesh in Jesus?

The Council of Ephesus (431), which addressed the doctrine of the personhood of Christ, sought to combat Nestorianism and its tendency to divide Christ into two distinct persons.12

To describe the union of the divine and human in Jesus, the council affirmed that "the Word, uniting to himself in his person the flesh animated by a rational soul, became man". This formulation emphasized the unity of the Incarnation, asserting that the divine Word and human flesh were indissolubly joined in one person. By insisting on this intimate union, the council supported the use of the title Theotokos ("God-bearer") for the Virgin Mary, rejecting the view that the human and divine natures existed independently.1234