Chapter 45. The Son may more appropriately be called the essence of the Fa... (Monologium (Meditations on the Being of God)) (Anselm of Canterbury, St.)

And although, for reasons we have noted, this is true, it is much more proper to call the Son the essence of the Father than the Father the essence of the Son. For, since the Father has his being from none other than himself, it is not wholly appropriate to say that he has the being of another than himself; while, since the Son has his being from the Father, and has the same essence with his Father, he may most appropriately be said to have the essence of his Father.

Hence, seeing that neither has an essence, except by being an essence; as the Son is more appropriately conceived to have the essence of the Father than the Father to have the essence of the Son, so the Son may more fitly be called the essence of the Father than the Father the essence of the son. For this single explanation proves, with sufficiently emphatic brevity, that the Son not only has the same essence with the Father, but has this very essence from the Father; so that, to assert that the Son is the essence of the Father is the same as to assert that the Son is not a different essence from the essence of the Father nay, from the Father essence.

In like manner, therefore, the Son is the virtue of the Father, and his wisdom, and justice, and whatever is consistently attributed to the essence of the supreme Spirit.