47 Glance over the whole course of time, and realise in what guise He appeared to Joshua the son of Nun, a prophet bearing His name, or to Isaiah, who relates that he saw Him, as the Gospel also bears witness, or to Ezekiel, who was admitted even to knowledge of the Resurrection, or to Daniel, who confesses the Son of Man in the eternal kingdom of the ages, or to all the rest to whom He presented Himself in the form of various created beings, for the ways of God and for the works of God, that is to say, to teach us to know God, and to profit our eternal state.
Why does this method, expressly designed for human salvation, bring about at the present time such an impious attack upon His eternal birth? The creation, of which you speak, dates from the commencement of the ages; but His birth is without end, and before the ages. Maintain by all means that we are doing violence to words, if a Prophet, or the Lord, or an Apostle, or any oracle whatever has described by the name of creation the birth of His eternal divinity. In all these manifestations God, Who is a consuming fire, is present, as created, in such a manner that He could lay aside the created form by the same power by which He assumed it, being able to destroy again that which had come into existence merely that it might be looked upon.
Source: On the Trinity (New Advent)