"Filioque" for the sake of declaring the truth

EUGENIUS IV 1431-1447
COUNCIL OF FLORENCE 1438-1445
Ecumenical XVII (Union with the Greeks, Armenians, Jacobites)

Decree for the Greeks *
[From the Bull "Laetentur coeli," July 6, 1439]
691 [The procession of the Holy Spirit] In the name of the Holy Trinity, of the Father, and of the Son, and of the Holy Spirit, with the approbation of this holy general Council of Florence we define that this truth of faith be believed and accepted by all Christians, and that all likewise profess that the Holy Spirit is eternally from the Father and the Son and has His essence and His subsistent being both from the Father and the Son, and proceeds from both eternally as from one principle and one spiration; we declare that what the holy Doctors and Fathers say, namely, that the Holy Spirit proceeds from the Father through the Son, tends to this meaning, that by this it is signified that the Son also is the cause, according to the Greeks, and according to the Latins, the principle of the subsistence of the Holy Spirit, as is the Father also. And since all that the Father has, the Father himself, in begetting, has given to His only begotten Son, with the exception of Fatherhood, the very fact that the Holy Spirit proceeds from the Son, the Son himself has from the Father eternally, by whom He was begotten also eternally. We define in addition that the explanation of words "Filioque" for the sake of declaring the truth and also because imminent necessity has been lawfully and reasonably added to the Creed.
692 We have likewise defined that the body of Christ is truly effected in and unleavened or leavened wheaten bread; and that priests ought to effect the body of our Lord in either one of these, and each one namely according to the custom of his Church whether that of the West or of the East
693 [ De novissimis] * It has likewise defined, that, if those truly penitent have departed in the love of God, before they have made satisfaction by the worthy fruits of penance for sins of commission and omission, the souls of these are cleansed after death by purgatorial punishments; and so that they may be released from punishments of this kind, the suffrages of the living faithful are of advantage to them, namely, the sacrifices of Masses, prayers, and almsgiving, and other works of piety, which are customarily performed by the faithful for other faithful according to the institutions of the Church. And that the souls of those, who after the reception of baptism have incurred no stain of sin at all, and also those, who after the contraction of the stain of sin whether in their bodies, or when released from the same bodies, as we have said before, are purged, are immediately received into heaven, and see clearly the one and triune God Himself just as He is, yet according to the diversity of merits, one more perfectly than another. Moreover, the souls of those who depart in actual mortal sin or in original sin only, descend immediately into hell but to undergo punishments of different kinds [see n.464].
694 We likewise define that the holy Apostolic See, and the Roman Pontiff, hold the primacy throughout the entire world; and that the Roman Pontiff himself is the successor of blessed Peter, the chief of the Apostles, and the true vicar of Christ, and that he is the head of the entire Church, and the father and teacher of all Christians; and that full power was given to him in blessed Peter by our Lord Jesus Christ, to feed, rule, and govern the universal Church; just as is contained in the acts of the ecumenical Councils and in the sacred canons.

Source:
Denzinger - English translation, older numbering
1177

Related:
Declaration Concerning the Procession of the …