V. The actions of Christ's two natures must be kept distinct.
Although therefore in our one Lord Jesus Christ, the true Son of God and man, the person of the Word and of the flesh is one, and both beings have their actions in common: yet we must understand the character of the acts themselves, and by the contemplation of sincere faith distinguish those to which the humility of His weakness is brought from those to which His sublime power is inclined: what it is that the flesh without the Word or the Word without the flesh does not do. For instance, without the power of the Word the Virgin would not have conceived nor brought forth: and without the reality of the flesh His infancy would not have laid wrapt in swaddling clothes.
Without the power of the Word the Magi would not have adored the Child that a new star had pointed out to them: and without the reality of the flesh that Child would not have been ordered to be carried away into Egypt and withdrawn from Herod's persecution. Without the power of the Word the Father's voice uttered from the sky would not have said, “This is My beloved Son, in whom I am well pleased:” and without the reality of the flesh John would not have been able to point to Him and say: “Behold the Lamb of God, behold Him that bears away the sins of the world.”
Without the power of the Word there would have been no restoring of the sick to health, no raising of the dead to life: and without the reality of the flesh He would not have hungered and needed food, nor grown weary and needed rest. Lastly, without the power of the Word, the Lord would not have professed Himself equal to the Father, and without the reality of the flesh He would not also have said that the Father was greater than He: for the Catholic Faith upholds and defends both positions, believing the only Son of God to be both Man and the Word according to the distinctive properties of His divine and human substance.
Source: Letters (New Advent)