The Light always, its Brightness always. Let God be allowed to beget an eternal Son. Of God are we speaking. Let the father stand still a while, and in his growing the son will follow on him, and you will see him equal. But see, I give you whereby to understand this.
Fire engenders a coeval brightness.
For fire begets brightness, yet is it never without brightness. Since then you see that the brightness is coeval with its fire, suffer God to beget a Coeternal Son.