Works of St. Anselm, tr. by Sidney Norton Deane, , at sacred-texts.com
Yet there are not three, but one Father and one Son and one Spirit.
AND here I see a question arises. For, if the Father is intelligence and love as well as memory, and the Son is memory and love as well as intelligence, and the Spirit is no less memory and intelligence than love; how is it that the Father is not a Son and a Spirit of some being? and why is not the Son the Father and the Spirit of some being? and why is not this Spirit the Father of some being, and the Son of p. 121 some being? For it was understood, that the Father was memory, the Son intelligence, and the Spirit love.
But this question is easily answered, if we consider the truths already disclosed in our discussion. For the Father, even though he is intelligence and love, is not for that reason the Son or the Spirit of any being; since he is not intelligence, begotten of any, or love, proceeding from any, but whatever he is, he is only the begetter, and is he from whom the other proceeds.
The Son also, even though by his own power he remembers and loves, is not, for that reason, the Father or the Spirit of any; since he is not memory as begetter, or love as proceeding from another after the likeness of his Spirit, but whatever being he has he is only begotten and is he from whom the Spirit proceeds.
The Spirit, too, is not necessarily Father or Son, because his own memory and intelligence are sufficient to him; since he is not memory as begetter, or intelligence as begotten, but he alone, whatever he is, proceeds or emanates.
What, then, forbids the conclusion that in the supreme Being there is only one Father, one Son, one Spirit, and not three Fathers or Sons or Spirits?