Chapter 23. This good is equally Father, and Son, and Holy Spirit. (Proslogium (Discourse on the existence of God)) (Anselm of Canterbury, St.)

And this is a single, necessary Being, which is every good, and wholly good, and the only good.�Since the Word is true, and is truth itself, there is nothing in the Father, who utters it, which is not accomplished in the Word by which he expresses himself. Neither is the love which proceeds from Father and Son unequal to the Father or the Son, for Father and Son love themselves and one another in the same degree in which what they are is good. Of supreme simplicity nothing can be born, and from it nothing can proceed, except that which is this, of which it is born, or from which it proceeds.

THIS good you are, you, God the Father; this is your Word, that is, your Son. For nothing, other than what you are, or greater or less than you, can be in the Word by which you express yourself; for the Word is true, as you are truthful. And, hence, it is truth itself, just as you are; no other truth than you; and you are of so simple a nature, that of you nothing can be born other than what you are. This very good is the one love common to you and to your Son, that is, the Holy Spirit proceeding from both. For this love is not unequal to you or to your Son; seeing that you love yourself and him, and he, you and himself, to the whole extent of your being and his. Nor is there aught else proceeding from you and from him, which is not unequal to you and to him. Nor can anything proceed from the supreme simplicity, other than what this, from which it proceeds, is.

But what each is, separately, this is all the Trinity at once, Father, Son, and Holy Spirit; seeing that each separately is none other than the supremely simple unity, and the supremely unitary simplicity which can neither be multiplied nor varied. Moreover, there is a single necessary Being. Now, this is that single, necessary Being, in which is every good; nay, which is every good, and a single entire good, and the only good.