Works of St. Anselm, tr. by Sidney Norton Deane, [1903], at sacred-texts.com
Only the Father begets and is unbegotten; only the son is begotten; only love neither begotten nor unbegotten.
STILL, it is apparent that this love can neither be said, in accordance with the usage of common speech, to be unbegotten, nor can it so properly be said to be begotten, as the Word is said to be begotten. For we often say of a thing that it is begotten of that from which it derives existence, as when we say that light or heat is begotten of fire, or any effect of its cause.
On this ground, then, love, proceeding from supreme Spirit, cannot be declared to be wholly unbegotten, but it cannot so properly be said to be begotten as can the Word; since the Word is the most true offspring and most true Son, while it is manifest that love is by no means offspring or son.
He alone, therefore, may, or rather should, be called begetter and unbegotten, whose is the Word; since he alone is Father and parent, and in no wise derives existence from another; and the Word alone should be called begotten, which alone is Son and offspring. But only the love of both is neither begotten nor unbegotten, because it is neither son nor off spring, and yet does in some sort derive existence from another.