A Thomist was trying to explain what eternal generation without causation. I asked Jimmy Stephens his comments on the issue:

The procession of the Word in God is called generation. In proof whereof we must observe that generation has a twofold meaning: one common to everything subject to generation and corruption; in which sense generation is nothing but change from non-existence to existence. In another sense it is proper and belongs to living things; in which sense it signifies the origin of a living being from a conjoined living principle; and this is properly called birth. Not everything of that kind, however, is called begotten; but, strictly speaking, only what proceeds by way of similitude. Hence a hair has not the aspect of generation and sonship, but only that has which proceeds by way of a similitude. Nor will any likeness suffice; for a worm which is generated from animals has not the aspect of generation and sonship, although it has a generic similitude; for this kind of generation requires that there should be a procession by way of similitude in the same specific nature; as a man proceeds from a man, and a horse from a horse. So in living things, which proceed from potential to actual life, such as men and animals, generation includes both these kinds of generation. But if there is a being whose life does not proceed from potentiality to act, procession (if found in such a being) excludes entirely the first kind of generation; whereas it may have that kind of generation which belongs to living things. So in this manner the procession of the Word in God is generation; for He proceeds by way of intelligible action, which is a vital operation:—from a conjoined principle (as above described):—by way of similitude, inasmuch as the concept of the intellect is a likeness of the object conceived:—and exists in the same nature, because in God the act of understanding and His existence are the same, as shown above (I:14:4). Hence the procession of the Word in God is called generation; and the Word Himself proceeding is called the Son.

SUMMA THEOLOGIAE: The procession of the divine persons (Prima Pars, Q. 27) (newadvent.org)

this is properly called birth

whereas it may have that kind of generation which belongs to living things.

(birth)

The conjoined principle is a matter of causality, no matter how much one wants to quibble about words.

The likening it to God’s understanding is (similar to Jonathan Edwards).

I take this to be a lot of obsolete (and in some cases vacuous) language that says the Son possesses a timeless birth. As God is always in a state or mode of knowledge, the Son is always in a state of birth. He doesn’t go from being unborn to born. He’s always in the being born.

But that’s just emanationism with different words.

Saying the Son is an effect of God via God’s nature is no less problematic than saying the creation is that kind of effect.

Insofar as creation would not be any more equal with God that way, neither is the Son.

Insofar as the Son need not be less God for being caused, neither is creation.

What makes creation creation is that it is caused.

That is the dividing line.

All this talk of birth without nonbeing is just talking about effects without causality. It’s unintelligible.