The Latin text (below my translation) can be found in Denzinger 846-847.
Indeed, with regard to this sacrament, He said to the Apostles, “Do this in remembrance of me” (Luke 22:19), that the especial, unique, and manifest memorial of His most excellent love, with which He loved us, might be for us this supreme and august sacrament. Miraculous is the memorial ... in which the sign is renewed and the wonderful things are transformed, in which is contained all delight, in which certainly we obtain support of life and salvation. This is the saving memorial, in which we bring to mind the dear memory of our redemption, in which we are brought back from evil and built up in goodness, and attain an increase of virtues and graces, in which we most certainly approach the bodily presence of the Savior Himself.In institutione quidem huius sacramenti dixit ipse Apostolis: 'Hoc facite in meam commemorationem' (Lc 22, 19), ut praecipuum et insigne memoriale sui amoris eximii, quo nos dilexit, esset nobis hoc praecelsum et venerabile sacramentum. Memoriale, inquam, mirabile ..., in quo innovata sunt signa et mirabilia immutata, in quo habetur omne delectamentum ..., in quo utique vitae suffragium consequimur et salutis. Hoc est memoriale ... salvificum, in quo gratam redemptionis nostrae recensemus memoriam, in quo a malo retrahimur et in bono confortamur et ad virtutum et gratiarum proficimus incrementa, in quo profecto proficimus ipsius corporali praesentia Salvatoris.
Note, on the one hand how we are gathered together in spirit and mind with those others whose memory we celebrate, but we do not obtain thereby their real presence. [But] in this sacramental commemoration of Christ, Jesus Christ is truly present, albeit under another form, He is truly with us in His very own substance. Indeed, as He was about to ascend into Heaven, He said to the Apostles and to their followers: “Behold, I am with you all days, even to the consummation of the world” (Matt. 28:20), comforting them by the gracious promise, that He would abide and be with them even in his bodily presence.
Transcending every fullness of bounty, exceeding all manner of love, He provides himself in this meal. O singular and admirable, O unique and extraordinary gift, whereby the Giver comes as gift, and the very same is given with the Giver inside. Therefore, He gives to us himself as sustenance, that, because man had been overcome by death [by food in Eden], even so He might be raised to life by food. A taste [of the food in Eden] mortally wounded man, and a taste [of this food] cured him. See this: because, whence the wound was sprung [from a tree (in the garden)], so came the cure [from a tree (the cross)], and whence death crept in, thence life came forth. Of the former tasting it is written accordingly: “In whatsoever day you eat [of it], you shall die to the death” (Gen. 2:17); of the latter [tasting], it reads truly: “If any man eat of this bread, he shall live for ever.” (John 6:52)
Such an appropriate gift and fitting work of the Holy Spirit came forth, that the Eternal Word of God, who is the food and refreshment of [us] rational creatures, was made flesh, that He may be given as food for a rational creature, for flesh and body, that is, for man. This bread is received [as food], but it is not truly “devoured;” it is eaten, but it is not changed, because in the eating it is not transformed at all, but, if it is received worthily, the one who receives it is conformed to Him.
Alia namque, quorum memoriam agimus, spiritu menteque complectimur, sed non propter hoc realem eorum praesentiam obtinemus. In hac vero sacramentali Christi commemoratione Iesus Christus praesens sub alia quidem forma, in propria vero substantia est nobiscum. Adscensurus enim in caelum dixit Apostolis et eorum sequacibus: 'Ecce ego vobiscum sum omnibus diebus usque ad consummationem saeculi' (Mt 28,20), benigna ipsos promissione confortans, quod remaneret et esset cum eis etiam praesentia corporali.
Transcendens omnem plenitudinem largitatis, omnem modum dilectionis excedens, attribuit se in cibum. O singularis et admiranda liberalitas, ubi donator venit in donum, et datum est idem penitus cum datore! ... Dedit igitur nobis se in pabulum, ut, quia per mortem homo corruerat, et per cibum relevaretur ad vitam. ... Gustus sauciavit, et gustus sanavit. Vide, quia, unde vulnus est ortum, prodiit et medela, et, unde mors subiit, exinde vita evenit. De illo siquidem gustu dicitur: 'Quacumque die comederis, morte morieris' (Gen 2, 17); de isto vero legitur: 'Si quis comederit ex hoc pane, vivet in aeternum' (Jo 6, 52). ...
Decens quoque liberalitas exstitit et conveniens operatio, ut Verbum Dei aeternum, quod rationabilis creaturae cibus est et refectio, factum caro, se rationabili creaturae carni et corpori, homini videlicet, in edulium largiretur. ... Hic panis sumitur, sed vere non consumitur; manducatur, sed non transmutatur, quia in edentem minime transformatur, sed, si digne recipitur, sibi recipiens conformatur.