You make me (and Jeremy and Dan) sound like the Terminator with the capital A like that. 
Boardhost has removed a lot of really helpful moderator features in the last year. It would be nice to get some of those back. It would also be nice to be able to split threads.

I also think it would just look nicer. (I know. I know: "It's a forum. Not the Louvre. Get over yourself, John." But I try to think like someone coming to the forum for the very first time and deciding whether to sign up, and seeing our rather late '90s-looking layout.) The dictum that “if it works, it's enough” has led to too many cities being paved with those ghastly cement blocks people now call buildings.

Johannes wrote:

Again, the subjects of the modes of Being are the respective Persons. You cannot call "He" either the essence as abstracted from the Persons or the Godhead (i.e. the three Persons at once).

You see, I have no idea how to square this explanation with divine simplicity. I'm not denying that the following is what Catholic dogma states:

The Subjects of the personal properties are the Persons, not the common essence. E.g. the property of paternity means that the Subject with that property generates/begets (a Son). But it is the Father Who begets, not the essence. This was expressly stated by the Ecumenical Council Lateran IV in 1215

I'm just not sure how, given God's absolute simplicity, we can have a common essence and a property of paternity that aren't just the same (strictly identical) thing. In other words, my question isn't what Catholic dogma is. It's how to assay it in a way compatible with divine simplicity. And I don't see that you've done that.

But I'm going to leave this conversation here and get back to other stuff I should be doing right now.

Johannes wrote:

Having said that, the Persons are not parts of the divine essence or of the Godhead, and therefore neither the essence nor the Godhead is ontologically complex.

Do you mean “mode” in the sense of “mode of Being”? This is what I thought at first. 

(I'm still not sure I see how something absolutely simple can have three distinct modes of Being without importing complexity into it. God doesn't exist three times. He exists once. In one way. But I would rather take it up when I have more time. I'm also not sure “paternity”, “filiation”, et al., are modes of Being. I'm willing to accept that a contingent, externally unified entity has a different mode of Being (i.e. contingent Being) from a necessary “being” whose essence is identical to his existence (i.e. necessary Being), or that a dependent being (e.g. an accident) has a distinct mode of Being (i.e. dependent Being) from an independent being (e.g. a substance with its independent Being); but talk of a “mode of Being of paternity” or a “mode of Being of filiation” just sounds like we're importing aspects of distinct essences into the essence of existence. Was my father's mode of Being distinct from mine in virtue of his being my father? But again, these are the kinds of conversations we should be having when I can afford to pay real attention to them.)

The Subsistent Act of Being in filiation mode does not stand in a real relation to Christ's human nature but in a relation of reason. It is Christ's human nature which stands in a real relation to the Subsistent Act of Being in filiation mode, specifically is actualized by Him, or, using terminology previous to the adoption of the Aristotelian act/potency framework, subsists in Him.

Right. Res respectivae (as opposed to relations construed as we tend to now) allow this kind of talk, but I've always been suspicious of it. (It's part of the very meaning and essence of “before” that if x is before y, y is after x. I make a similar complaint about a one-sided similarity relation in another really old post here.) It sounds like a narrowly logical (as opposed to a strictly or broadly logical) or conceptual absurdity.

(ii) The Subsistent Act of Being in filiation mode started to actualize Christ's human nature at the moment of the creation of said nature.

I don't see how this explains how the Subsistent Act of Being, God, can stand in temporal relations and “before” and “after” are, unless you mean them in some other sense, temporal relations.