Proslogium and Monologium/Monologium/Chapter37

Chapter XXXVII
Whatever his relation to his creatures, this relation his Word also sustains: yet both do not simultaneously sustain this relation as more than one being.

But since it has already been clearly demonstrated that the supreme Spirit created all things through his Word, did not the Word itself also create all things? For, since it is consubstantial with him, it must be the supreme essence of that of which it is the Word. But there is no supreme Essence, except one, which is the only creator and the only beginning of all things which have been created. For this Essence, through no other than itself, alone created all things from nothing. Hence, whatever the supreme Spirit creates, the same his Word also creates, and in the same way.

Whatever relation, then, the supreme Spirit bears to what he creates, this relation his Word also bears, and in the same way. And yet, both do not bear it simultaneously, as more than one, since there are not more supreme creative essences than one. Therefore, just as he is the creator and the beginning of the world, so is his Word also; and yet there are not two, but one creator and one beginning.