The following is a juxtaposition of part of an ancient text known as "de Sacramentis", usually attributed to St. Ambrose of Milan, and the canon of the traditional Catholic Mass of the Roman rite.  The conclusion from this comparison is that the central part of the traditional Roman canon was already fairly well in place by sometime in the late 4th century.  Taken from "The Mass of the Western Rites", by the Right Reverend Dom Fernand Cabrol, Abbot of Farnborough, 1934, without permission. Excerpted from Chapter VI: THE MASS AT ROME, FROM THE FIFTH TO THE SEVENTH CENTURIES.  The paragraph at the end is from the book, not me.  Sorry about the long lines.  Joe Buehler  -----  TEXT OF DE SACRAMENTIS          ROMAN CANON                     ROMAN CANON (about 400 AD)                  (1962 AD)                       (English translation)                                  Te igitur ...                   (omitted here)                                 Memento Domine ...                                 Communicantes ...                                 Hanc igitur oblationem ...  Fac nobis (inquit sacerdos),    Quam oblationem tu Deus, in     Do thou, O God, deign to hanc oblationem ascriptam,      omnibus, quaesumus,             bless what we offer, and ratam, rationabilem,            benedictam, adscriptam,         make it approved, acceptabilem, quod figura       ratam, rationabilem,            effective, right, and est corporis et sanguinis       acceptabilemque facere          wholly pleasing in every Jesu Christi.                   digneris: ut nobis corpus et    way, that it may become                                 sanguis fiat dilectissimi       for our good, the Body                                 Filii tui Domini nostri Jesu    and Blood of Thy dearly                                 Christi.                        beloved Son, Jesus Christ                                                                 our Lord.  Qui pridie quam pateretur,      Qui pridie quam pateretur,      Who, the day before He in sanctis manibus suis         accepit panem in sanctas ac     suffered, took bread into accepit panem, respexit in      venerabiles manus suas: et      His holy and venerable caelum ad te, sancte Pater      elevatis oculis in ccelum,      hands, and having raised omnipotens, aeterne Deus,       ad Te Deum Patrem suum          His eyes to Heaven, unto Gratias agens, benedixit,       omnipotentem, tibi gratias      Thee, O God, His Almighty fregit, fractum quae            agens, benedixit, fregit,       Father, giving thanks to apostolis suis et discipulis    deditque discipulis suis        Thee, He blessed it, broke suis tradidit dicens:           dicens: accipite et             it, and gave it to His accipite et edite ex hoc        manducate ex hoc omnes: hoc     disciples, saying: Take ye omnes: hoc est enim corpus      est enim corpus meum.           all and eat of this: meum, quod pro multis                                           For this is my Body. confringetur.  Similiter etiam calicem         Simili modo postquam            In like manner, when the postquam caenatum est,          caenatum est, accipiens et      supper was done, taking pridie quam pateretur,          hunc praeclarum calicem in      also this goodly chalice accepit, respexit in            sanctas ac venerabiles manus    into His holy and caelum ad te, sancte pater      suas item tibi gratias          venerable hands, again omnipotens, aeterne Deus,       agens, benedixit deditque       giving thanks to Thee, gratias agens, benedixit,       discipulis suis, dicens:        He blessed it, and gave it apostolis suis et discipulis    accipite et bibite ex eo        to His disciples, saying: suis tradidit, dicens:          omnes: Hic est enim calix       Take ye all, and drink of accipite et bibite ex hoc       sanguinis mei, novi et          this: For this is the omnes: hic est enim sanguis     aeterni testamenti:             Chalice of my Blood of the meus.                           mysterium fidei; qui pro        new and eternal covenant;                                 vobis et pro multis             the mystery of faith,                                 effundetur in remissionem       which shall be shed for                                 peccatorum.                     you and for many unto the                                                                 forgiveness of sins.                                  Haec quotiescumque feceritis    As often as you shall do                                 in mei memoriam facietis.       these things, in memory of                                                                 Me shall you do them.  Ergo memores gloriosissimae     Unde et memores, Domine, nos    Mindful, therefore, O ejus passionis et ab inferis    servi tui, sed et plebs tua     Lord, not only of the resurrectionis, in caelum       sancta, ejusdem Christi         blessed Passion of the ascensionis, offerimus tibi     Filii tui Domini nostri, tam    same Christ, Thy Son, our hanc immaculatam hostiam,       beatae passionis necnon et      Lord, but also of His hunc panem sanctum et           ab inferis resurrectionis,      resurrection from the calicem vitae aeternae;         sed et in caelos gloriosae      dead, and finally His                                 ascensionis: offerimus          glorious ascension into                                 praeclarae majestati tuae de    Heaven, we, Thy ministers,                                 tuis donis ac datis, hostiam    as also Thy holy people,                                 puram, hostiam sanctam,         offer unto Thy supreme                                 hostiam immaculatam, Panem      majesty, of the gifts                                 sanctum vitae aeternae, et      bestowed upon us, the                                 Calicem salutis perpetuae.      pure Victim, the holy                                                                 Victim, the all-perfect                                                                 Victim: the holy Bread of                                                                 life eternal and the                                                                 Chalice of unending                                                                 salvation.  et petimus et precamur, ut      Supra quae propitio ac          And this do Thou deign to hanc oblationem suscipias in    sereno vultu respicere          regard with gracious and sublimi altari tuo per manus    digneris: et accepta habere,    kindly attention and hold angelorum tuorum sicut          sicuti accepta, habere          acceptable, as Thou didst suscipere dignatus es munera    dignatus es munera pueri tui    deign to accept the pueri tui justi Abel et         justi Abel, et sacrificium      offerings of Abel, Thy sacrificium patriarchae         patriarchae nostri Abrahae,     just servant, and the nostri Abrahae et quod tibi     et quod tibi obtulit summus     sacrifice of Abraham our obtulit summus sacerdos         sacerdos tuus Melchisedech      patriarch, and that which Melchisedech.                   sanctum sacrificium,            Thy chief priest                                 immaculatam hostiam.            Melchisedech offered unto                                                                 Thee, a holy sacrifice and                                                                 a spotless victim.                                  Supplices te rogamus,           Most humbly we implore                                 omnipotens Deus: jube haec      Thee, almighty God, bid                                 perferri per manus sancti       these offerings to be                                 Angeli tui in sublime altare    brought by the hands of                                 tuum in conspectu divinae       Thy holy angel unto Thy                                 majestatis tuae: etc.           altar above; before the                                                                 face of Thy Divine                                                                 Majesty; etc.