In that encyclical he plainly states that the Earth may not be the centre of the universe.

OK, will they accept the matrimonial ruling of Florence Fourth Lateran Council as indicating that the theory of four humours is valid? The generations each branch need have passed from a common ancestor were being reduced from seven to only four. The REASON given is the four humours:

Moreover the prohibition against marriage shall not in future go beyond the fourth degree of consanguinity and of affinity, since the prohibition cannot now generally be observed to further degrees without grave harm. The number four agrees well with the prohibition concerning bodily union about which the Apostle says, that the husband does not rule over his body, but the wife does; and the wife does not rule over her body, but the husband does; for there are four humours in the body, which is composed of the four elements.

Especially, if, as in this case, the decree is perpetual. Quoting further:

Although the prohibition of marriage is now restricted to the fourth degree, we wish the prohibition to be perpetual, notwithstanding earlier decrees on this subject issued either by others or by us. If any persons dare to marry contrary to this prohibition, they shall not be protected by length of years, since the passage of time does not diminish sin but increases it, and the longer that faults hold the unfortunate soul in bondage the graver they are.

In other words, the decree claims infallibility in at least moral theology.

This document is clearly superior in order of dignity to a mere encyclical of a following Pope, such as Benedict XV.

Also, the four humours are here given as a direct REASON for the new discipline, which, as said, claims infallibility.

Nowhere in In Praeclara Summorum is Pope Benedict XV directly claiming infallibility. What is more, not only is "Earth may not be the centre of the universe" not the topic, but it is not even a reason, merely a concession. A very obvious concession due to his speaking in a very loudly confident heliocentric Italy. One can compare what Papacy suffered from 1870 on to what Russians suffered from 1917 on. And one can compare Mussolini to Gorbatchev. That is, the year of In Praeclara Summorum, the Church was acting in a persecution. A bit like Russian Patriarchate when going MUCH further and directly endorsing Evolution.

So, the best Benedict XV can give the critics and perhaps persecutors of the Church is a concessive clause in the subjunctive?

If Benedict XV "plainly states" - namely as a canonic fact, a doctrinal clear possibility - that Earth could be moving around something else and around herself each day, which is what not being the centre of the universe comes out to, how does Lateran IV, when speaking with a clear claim of infallibility, not "plainly state" that the body has four humours, that it is composed of four elements?

If that passage can be an obiter dictum in Lateran IV, how can the very roundabout phrase "licet ad universi caeli complexum iam non quasi centrum, ut opinio fuit, obtinere dicenda sit," which by my own translation is "even if it be (sit) not (non) necessary to say of her (dicenda) that she obtains so to say the centre to the complex of universal heaven as the opinion was" not be an obiter dictum?

Actually, even if I mistranslated slightly in heat of argument and fatigue, and "non dicenda" should be taken as "not apt to say of her" rather than as "not necessary to say of her" (though literally "non dicendum est" is "it is not necessary to say", it is often used as "it is necessary not to say" or "it is not apt to say"), it is still an oblique clause in a totally different argument. It cannot be compared to Pope Leo XIII reference to phenomenal language (without specifying how it would apply to geo-/helio-debate!) which is to the point, but without a clear favour to heliocentrism. It comes in "licet non dicenda sit". That is one removed from "plainly stating.

By 2:15 Vatican Catholic has referred to a person thinking the Pope "only mentioning it in a hypothetical argument".

But, he refuses to disclose that In Praeclara Summorum doesn't have topical room for being an outlet for a definition on Earth's position. It is still about "even if not this and this and this" (as Vatican Catholic resumes), we are dealing with an even so "Dante's Divina Commedia is an edifying book" - which was the exact subject of In Praeclara Summorum, as it was issued with occasion of a Dante jubilee.

2:34 "that is obviously ridiculous when you consider the passage in context, as we pointed out in the e-exchanges".

Here is the passage he wants to quote:

If the progress of science showed later that that conception of the world rested on no sure foundation, that the spheres imagined by our ancestors did not exist, that nature, the number and course of the planets and stars, are not indeed as they were then thought to be, still the fundamental principle remained that the universe, whatever be the order that sustains it in its parts, is the work of the creating and preserving sign of Omnipotent God, who moves and governs all, and whose glory risplende in una parte piu e meno altrove; and though this earth on which we live may not be the centre of the universe as at one time was thought, it was the scene of the original happiness of our first ancestors, witness of their unhappy fall, as too of the Redemption of mankind through the Passion and Death of Jesus Christ. Therefore the divine poet depicted the triple life of souls as he imagined it in a such way as to illuminate with the light of the true doctrine of the faith the condemnation of the impious, the purgation of the good spirits and the eternal happiness of the blessed before the final judgment.

But the opening of the paragraph could refer to Tycho Brahe refuting solid spheres and to more celestial bodies being found (Moons of Jupiter, Pluto, and so on) and - here I have a misgiving - he could have believed at least conditionally that unlike St Thomas and Dante thinking celestial bodies are moved by angels, that the mechanistic view of their motions, the Newtonian-causes only one, was correct. However, he could also have referred to a Nova proving stars are not sempiternal. They don't remain unconditionally unchanging, barring miracles of their creation and perhaps falling down (Matthew 24, if taken literally about stars rather than typologically about bishops, and the "falling from heaven" of their apostasy).

Here I'll have to end for this evening, internet time is running up.

Tomorrow, if God speeds my intention, we'll see what Vatican Catholic does with the paragraph.