For now, I would like to ask you where you get the notion that the sending of the Spirit is within the confines of time?
Because Christ Himself says, "When
the Helper comes, whom I will
send to you...". This definitively places the sending of the Holy Spirit as a temporal event, once which will
occur at a later date than Christ's statement about what He will
do in the future.
Furthermore, theologicially speaking (I mean notwithstanding the canonical issue of the addition of the text), the difference between the Latin and Eastern Churches on the matter is, like so much else, really only a matter of misunderstanding of terms - namely, the difference between the Greek word ekporeusai and the Latin word procedit, and the difference in understanding in the Latin and Eastern Traditions of the terms hypostasis, ousia and substance.
That may have (probably was) true when the filioque was first introduced and spread through the West. However, with the synodical definiations made at Lateran IV and Florence, the Roman Church clarified that of the possibile interpretations of the filioque, they were going with the subordinationist one.
As to the discussion in the rest of this thread, so long as you assert "Will" into the origination of the Son and the Holy Spirit, you are in the same category as Arius, putting the Son and the Holy Spirit in the same category as created things rather than the Uncreate. Will always involves multiple options, whether its the simple duality of 'do or not do' or as infinitely open as which star in the night sky to you choose to study. God 'willed' to create the Universe, and thus we confess the possibility that He could have willed to not create
the Universe. If the Father 'willed' to generate the Son and inspirate the Spirit, then we are confessing the possibility that He could will not to generate the Son or inspirate the Spirit.
Appealing to "God is not subject to change" does not alter this. God willed to create the Universe, and since God is not subject to change there was no *actual* possibility that He would change His mind and not create the Universe. But there because it was an act of will it remains at least a theoretical possibility. If the Father willed the Son and Holy Spirit into being, it might be as certain that they would exist as it is that the Universe would, as products of Who God the Father is. But they would still be like us, products of who God is--not God themselves.
(Note: this is different than the argument bogdan appears to be making. He is speaking of the the Godhead willing Itself into existence all by the same will. So the Divine Will which wills the Father into existence is the same will which wills the begetting of the Son and Procession of the Spirit, the Will which is shared by all 3 Persons of the Trinity. This is different from the claim earlier in the thread that the *Father* wills the Spirit into existence.)
Latin Catholics do not distinguish between action and being within the Godhead - that's the idea of divine simplicity.
Actually, this is the underlying problem with the filioque--why do Latin Catholics think they are qualified to comment upon anything *within the Godhead*, beyond what the Godhead has chosen to reveal to us?