154 Cf. DS 291; 294; 427; 442; 503; 571; 1880.
CITED TEXT:
St. Leo the Great, Epistle Lectis dilectionis tuae (449): DS 291
Likewise the only-begotten and eternal [Son] of the eternal Father "was born of the Holy Spirit and the Virgin Mary". This temporal birth in no way diminishes or adds to the eternal birth, but is entirely expended in restoring man who had been deceived so that he might conquer death and destroy by his own strength the devil who had dominion over death. For we cannot conquer the author of sin and death unless [the Son] takes up our nature and makes it his own, he whom neither sin can defile nor death restrain.
Indeed he was conceived by the Holy Spirit within the womb of the virgin mother, who bore him without losing her virginity just as she conceived without losing her virginity.
St. Leo the Great, Epistle Lectis dilectionis tuae (449): DS 294
Consequently, the Son of God entered into these lowly conditions of the world, after descending from His celestial throne, and though He did not withdraw from the glory of the Father, He was generated in a new order and in a new nativity. In a new order, because invisible in His own, He was made visible in ours; incomprehensible [in His own], He wished to be comprehended; permanent before times, He began to be in time; the Lord of the universe assumed the form of a slave, concealing the immensity of His majesty; the impassible God did not disdain to be a passible man and the immortal [did not disdain] to be subject to the laws of death. Moreover, He was generated in a new nativity, because inviolate virginity [that] did not know concupiscence furnished the material of His body. From the mother of the Lord, nature, not guilt, was assumed; and in the Lord Jesus Christ born from the womb of the Virgin, because His birth was miraculous, nature was not for that reason different from ours. For He who is true God, is likewise true man, and there is no falsehood in this unity, as long as there are alternately the lowliness of man and the exaltedness of the Divinity. For, just as God is not changed by His compassion, so man is not destroyed by His dignity. For each nature does what is proper to it with the mutual participation of the other; the Word clearly effecting what belongs to the Word, and the flesh performing what belongs to the flesh. One of these gleams with miracles; the other sinks under injuries. And just as the Word does not withdraw from the equality of the paternal glory, so His body does not abandon the nature of our race.
Council of Constantinople II (553): DS 427
If anyone says that the holy glorious ever-virgin Mary is falsely but not truly the Mother of God; or (is the Mother of God) according to relation, as if a mere man were born, but as if the Word of God became incarnate [and of her] from her, but the birth of the man according to them being referred to the Word of God as being with the man when he was born, and falsely accuses the holy synod of Chalcedon of proclaiming the Virgin Mother of God according to this impious conception which was invented by Theodore; or, if anyone calls her the mother of the man or the mother of the Christ, as if the Christ were not God, but does not confess that she is exactly and truly the Mother of God, because God the Word, born of the Father before the ages, was made flesh from her in the last days, and that thus the holy Synod of Chalcedon confessed her (to be), let such a one be anathema.
Pope Pelagius I, Letter (557): DS 442
Of this holy and blessed and consubstantial Trinity I believe and I confess that one person, that is, the Son of God in these last days descended from heaven, without leaving the Fatherly seat nor the government of the world, and that the Holy Spirit came upon the Virgin Mary and the power of the Most High overshadowed her, that this Word and Son of God mercifully entered the womb of the same holy Virgin Mary and from her flesh united to herself flesh animated by a rational and intellectual soul; nor that the Son of God first created flesh and afterwards came into it but as it is written, "wisdom built herself a house" so that as soon as there was flesh in the womb of the Virgin, it was the flesh of the Word of God, whence, without any permutation or change of the Word or of nature's flesh, the Word and Son of God was made man, one in both natures, that is, the divine and human natures, and that Christ Jesus true God and the same true man proceeded, that is, was born, while his mother's virginity remained intact: for the Virgin remained such in bearing him just as she had in conceiving him. On account of this we confess that the same blessed virgin Mary is truly Mother of God: for she bore the incarnate Word of God. Therefore one and the same Jesus Christ is the true Son of God and also true son of man, perfect in divinity and likewise perfect in humanity, so that he exists totally in what is his and totally in what is ours; and by a second birth he took up from man, his mother, what he was not, in such a way that he did not cease being what by the first birth, from the Father, he was. For this reason we believe him to be from two natures and in two natures which remain undivided and unconfused: undivided certainly because even after the assumption of our nature the one Christ remained and remains Son of God: unconfused, however, because we believe the natures to be so united in one person and subsistence that each retains its properties and neither is converted into the other. And therefore, as we have often said, we confess one and the same Christ to be true Son of God, and the same to be true son of man, consubstantial with the Father according to divinity and consubstantial with us according to humanity, like us in all things except sin; able to suffer in the flesh, the very same unable to suffer in divinity. We confess that he freely suffered in the flesh under Pontius Pilate for our salvation, died in the flesh, rose the third day, in the same flesh glorified and incorruptible, and . . . ascended into heaven and sits at the right hand of the Father.
Lateran Council (649): DS 503
If anyone does not properly and truly confess in accord with the holy Fathers, that the holy Mother of God and ever Virgin and immaculate Mary in the earliest of the ages conceived of the Holy Spirit without seed, namely, God the Word Himself specifically and truly, who was born of God the Father before all ages, and that she incorruptibly bore [Him?], her virginity remaining indestructible even after His birth, let him be condemned.
Creed of the Council of Toledo XVI (693): DS 571
Hence, although the works of the Trinity are inseparable, still we faithfully profess . . . that it was not the whole Trinity that took up flesh, but only the Son of God, who is begotten before all ages from the substance of God the Father, was born of the Virgin Mary at the end of the ages as the Gospel testifies when it says "the Word was made flesh and dwelt among us". . . . The angel's greeting when he says that the Holy Spirit will come upon her and proclaims that the power of the Most High, which is the Son of God the Father, will overshadow her, shows that the entire Trinity cooperates in the flesh of that same Son. And as the Virgin acquired the modesty of virginity before conception, so also she experienced no loss other integrity; for she conceived a virgin, gave birth a virgin, and after birth retained the uninterrupted modesty of an intact virgin.
Council of Trent (1555): DS 1880 Since the depravity and iniquity of certain men have reached such a point in our time that, of those who wander and deviate from the Catholic faith, very many indeed not only presume to profess different heresies but also to deny the foundations of the faith itself, and by their example lead many away to the destruction of their souls, we, in accord with our pastoral office and charity, desiring, in so far as we are able with God, to call such men away from so grave and destructive an error, and with paternal severity to warn the rest, lest they fall into such impiety, all and each who have hitherto asserted, claimed or believed that Almighty God was not three in persons and of an entirely uncomposed and undivided unity of substance and one single simple essence of divinity; or that our Lord is not true God of the same substance in every way with the Father and the Holy Spirit, or that He was not conceived of the Holy Spirit according to the flesh in the womb of the most blessed and ever Virgin Mary, but from the seed of Joseph just as the rest of men; or that the same Lord and our God, Jesus Christ, did not submit to the most cruel death of the Cross to redeem us from sins and from eternal death, and to reunite us with the Father unto eternal life; or that the same most blessed Virgin Mary was not the true mother of God, and did not always persist in the integrity of virginity, namely, before bringing forth, at bringing forth, and always after bringing forth, on the part of the omnipotent God the Father, and the Son, and the Holy Spirit, with apostolic authority we demand and advise, etc.
Don't see the word sex there.
Peace