Light from Light

Today, we hear the story about The Israelites who were bitten by snakes but as soon as they looked at the bronze serpent, they were healed.  It foreshadows the Son of God who is lifted up on the cross, and reconciled humanity to the Father.  

Someone asked me this question recently: what does light from light mean in the creed?  Is there a good analogy or expression to help us understand this.  I know that Jesus is truly the light of the world.  What does the Church teach in regards Light from Light?

To answer the question, is to look to the Catechism for some help.  The Catechism says that The faith of all Christians rests on the Trinity. (CCC 232)

CCC 240 to 242 state:

240 Jesus revealed that God is Father in an unheard-of sense: he is Father not only in being Creator; he is eternally Father in relation to his only Son, who is eternally Son only in relation to his Father: "No one knows the Son except the Father, and no one knows the Father except the Son and any one to whom the Son chooses to reveal him."

241 For this reason the Apostles confess Jesus to be the Word: "In the beginning was the Word, and the Word was with God, and the Word was God"; as "the image of the invisible God"; as the "radiance of the glory of God and the very stamp of his nature".

242 Following this Apostolic tradition, the Church confessed at the first ecumenical council at Nicaea (325) that the Son is "consubstantial" with the Father, that is, one only God with him. The second ecumenical council, held at Constantinople in 381, kept this expression in its formulation of the Nicene Creed and confessed "the only-begotten Son of God, eternally begotten of the Father, light from light, true God from true God, begotten not made, consubstantial with the Father".

God the Father is the Light that always was. God the Father has no beginning and no end. His Son, Jesus, is eternally begotten of the Father and consubstantial, or (of one substance) with His Father, the difference between the Father and Son is found within the relation.

His relationship with the Father, Sonship, and that he was eternally begotten of the Father for our salvation; and became man.

So He was Light (God the Son, Jesus) from Light (God, the Father), begotten not made.

Eternally begotten means He was incarnated 100% True God and 100% True Man; a man like us in all things but sin.

If a man and woman beget a child, the resulting child is not some other kind of animal, rather, that child is a human.

The same is true with Jesus. Because he was eternally begotten of the God the Father, he is a Divine person with two natures.  It is an error to say that Christ is a human person. 

Jesus is the Light that is eternally begotten from the Father and born incarnated in the womb of the Virgin Mary. He is 100% man while also being 100% God.

Light from Light does not imply, in any way, that the Blessed Virgin Mary was the Mother of God the Father. A human mother cannot give birth to a nature; only a human person, or in this case, 

a divine person, Jesus.

The only person Mary gave birth to was the Second Person of the Blessed Trinity, Jesus, Our True God and True Man. Mary is the daughter of God the Father.

I believe in one Lord Jesus Christ, eternally begotten of the Father, light from light, true God from true God, begotten not made, consubstantial to the Father.