Therefore, the substance of the Father is designated as the Son by the prophetic oracles long ago, as Solomon says: For you showed your substance and sweetness, which you have for your sons (Wis. 16:21), which appeared to have flowed down to the people of Israel from heaven in the form and image of heavenly bread. The Lord Himself explained this in the…

From the books of the Old Testament and then also from those of the New, we are taught that the Father, the Son and the Holy Spirit are of a single substance. Indeed, the book of Genesis begins, "In the beginning God created the heavens and the earth. Now the earth was invisible and shapeless, and darkness was over the abyss, and the Spirit of God moved…