Proslogium and Monologium/Monologium/Chapter58

Chapter LVIII
As the Son is the essence or wisdom of the Father in the sense that he has the same essence or wisdom that the Father has: so likewise the Spirit is the essence and wisdom etc. of Father and Son.

Also, just as the Son is the substance and wisdom and virtue of the Father, in the sense that he has the same essence and wisdom and virtue with the Father; so it may be conceived that the Spirit of both is the essence or wisdom or virtue of Father and Son, since it has altogether the same essence, wisdom, and virtue with these.