The Gospel is "proclaimed" because it is the "Good News" and Saint Paul speaks about proclaiming it. The Lesson and Epistle are "read" because they are written documents.
The Deacon was given the privilege of proclaiming the Gospel early on and has become a part of his "job description" so to speak. From the Catholic Encyclopedia:
The special duty of the deacon to read the Gospel seems to have been recognized from an early period, but it does not at first appear to have been so distinctive as it has become in the Western Church. Sozomen says of the church of Alexandria that the Gospel might only be read by the archdeacon, but elsewhere ordinary deacons performed that office, while in other churches, again it devolved upon the priests. It may be this relation to the Gospel which led to the direction in the Apostolic Constitutions (VIII, iv), that the deacons should hold the book of the Gospels open over the head of a bishop elect during the ceremony of his consecration. With the reading of the Gospel should also probably be connected the occasional, though rare, appearance of the deacon in the office of preacher. The second Council of Vaison (529) declared that a priest might preach in his own parish, but that when he was ill a deacon should read a homily by one of the Fathers of the Church, urging that deacons, being held worthy to read the Gospel were a fortiori worthy of reading a work of human authorship. Actual preaching by a deacon, however, despite the precedent of the deacon Philip, was at all periods rare, and the Arian bishop of Antioch, Leontius, was censured for letting his deacon Aetius preach. (Philostorgias, III, xvii). On the other hand, the greatest preacher of the East Syrian Church, Ephraem Syrus, is said by all the early authorities to have been only a deacon, though a phase in his own writings (Opp. Syr., III, 467, d) throws some doubt upon the fact. But the statement attributed to Hilarius Diaconus, nunc neque diaconi in popolo praedicant (nor do the deacons now preach to the people), undoubtedly represents the ordinary rule, both in the fourth century and later.
The Gospel has been for many centuries in East and West the privilege of the deacon. This was not always the case. At first a reader (anagnostes, lector) read all the lessons. We have seen a case of this in the story of St. Cyprian and Aurelian (see above). St. Jerome (died 420) speaks of the deacon as reader of the Gospel (Ep. cxlvii, n. 6), but the practice was not yet uniform in all churches. At Constantinople, on Easter day, the bishop did so (Sozom., H. E., vii, 19); in Alexandria, it was an archdeacon (ibid., he says that: "in other places deacons read the Gospel; in many churches only priests"). The Apostolic Constitutions refer the Gospel to the deacon; and in 527 a council, at Vaison, says deacons "are worthy to read the words that Christ spoke in the Gospel" (Baudot, op. cit., 51). This custom became gradually universal, as is shown by the formul� that accompany the tradition of the Gospel-book at the deacon's ordination (the eleventh century Visigothic "Liber ordinum" has the form: "Ecce evangelium Christi, accipe, ex quo annunties bonam gratiam fidei populo", Baudot, p. 52). [ Behold the Gospel of Christ, accept it, from which you may faithfully proclaim the good news to the people. ] An exception that lasted through the Middle Ages was that at Christmas the emperor, dressed in a rochet and stole, sang the midnight Gospel: "Exiit edictum a C�sare Augusto" etc. (Mabillon, "Mus�um italicum", I, 256 sq.). Another mark of respect was that everyone stood to hear the Gospel, bareheaded, in the attitude of a servant receiving his master's orders (Apost. Const., II, 57, and Pope Anastasius I, 399-401, in the "Lib. Pontif."). Sozomenos (H. E., VII, 19) is indignant that the Patriarch of Alexandria sate ("a new and insolent practice"). The Grand Masters of the Knights of St. John drew their swords while the Gospel was read. This custom seems still to be observed by some great noblemen in Poland. If any one has a stick in his hand he is to lay it down (Baudot, 116), but the bishop holds his crosier (see below). The Gospel was sung from the ambo (ambon), a pulpit generally halfway down the church, from which it could be best heard by every one (Cabrol, Dict. d'arch�ol. chr�t. et de liturgie, Paris, 1907, s.v. "Ambon", I, 1330-47). Often there were two ambos: one for the other lessons, on the left (looking from the altar); the other, for the Gospel, on the right. From here the deacon faced south, as the "Ordo Rom. II" says (Mabillon, Mus�um italic., II, 46), noting that the men generally gather there. Later, when the ambo had disappeared, the deacon turned to the north. Micrologus (De missa, ix) notices this and explains it as an imitation of the celebrant's position at the altar at low Mass � one of the ways in which that service has reacted on to high Mass. The Byzantine Church still commands the deacon to sing the Gospel from the ambo (e.g. Brightman, op. cit., 372), though with them, too, it has generally become only a theoretical place in the middle of the floor. The deacon first asked the blessing of the bishop (or celebrant) then went to the ambo with the book, in procession, accompanied by lights and incense. Germanus of Paris (died 576) mentions this (Ep. 1, P. L., LXXII, 91; cf. Durandus. "Ration.", IV, 24). See the ceremonies in the "Ordo Rom. I", 11, and "Ordo Rom. II", which are almost exactly ours. Meanwhile the Gradual was sung (see GRADUAL). The "Dominus vobiscum" at the beginning, the announcement of the Gospel ("Sequentia sancti Evangelii" etc.), and the answer, "Gloria tibi Domine", are also mentioned by the sixth-century Germanus (loc. cit.). At the end of the Gospel the people answered, "Amen", or "Deo Gratias", or "Benedictus qui venit in nomine Domini" (Durandus, "Rationale", IV, 24; Beleth, "Rationale", XXXIX; St. Benedict's Rule, XI). Our present answer, "Laus tibi Christe", seems to be a later one (Gihr, "Messopfer", 444). The elaborate care taken to decorate the book of the Gospels throughout the Middle Ages was also a sign of respect for its contents; St. Jerome speaks of this (Ep. xxii, 32). In a collection of manuscripts the Evangeliaria nearly always stand out from the rest by their special sumptuousness. They are not uncommonly written in gold and silver letters on vellum stained purple � the extreme limit of medieval splendour. The bindings, too, are nearly always adorned with special care. It is on Gospel books that one generally sees ivory carvings, metal-work, jewellery, enamel, sometimes relics. (For descriptions see Baudot, op. cit., 58-69.) The same tradition continues in the East. Allowing for doubtful modern taste in Greece, Russia, Syria, etc., the Euaggelion is still the handsomest book, often the handsomest object in a church. When it is not in use it generally displays the enamels of its cover on a desk outside the Iconostasis. To kiss the book was always from early times a sign of respect. This was done at one time not only by the celebrant and deacon, but by all the people present ("Ordo Rom. II", 8). Honorius III (1216-27) forbade this; but the book is still kissed by any high prelates who may be present (C�rim. epise., I, 30; Gihr, op. cit., 445). For this and similar ceremonies see Baudot (op. cit., 110-19). When the ambo disappeared in the West the sub-deacon held the book while the Gospel was sung by the deacon. He also carried it first to lay it on the altar (Amalarius of Metz: "De. Eccl. offic.", P. L., CV, 1112; Durandus, loc. cit.). The deacon made the sign of the cross first on the book and then on himself � taking a blessing from the book ("Ordo Rom. I", 11, "ut sigilletur"; Durandus, loc. cit., etc.; Beleth, XXXIX). The meaning of all these marks of reverence is that the Gospel-book, which contains Christ's words, was taken as a symbol of Christ himself. It was sometimes carried in the place of honour in various processions (Beissel, op. cit., 4); something of the same idea underlay the practice of putting it on a throne or altar in the middle of the synods (Baudot, 109-110. During provincial and general synods the Gospel is to be sung at each session. � C�r. Episc. I, xxxi, 16), and the superstitious abuses that afterwards developed, in which it was used for magic (ibid., 118; Catalani, "de codice S. Evangelii", III, see below). The Byzantine Church has developed the ceremony of carrying the Evangelion to the ambo into the elaborate rite of the "Little Entrance" (Fortescue, "Divine Liturgy of St. John Chrysostom", London, 1908, 68-74), and all the other Eastern Churches have similar stately ceremonies at this point of the Liturgy (Brightman, op. cit., for each rite). Another special practice that may be noticed here is that at a papal high Mass the Gospel (and the Epistle too) is read in Latin and Greek. This is already noticed by the first Roman Ordo (40). At Constantinople the Patriarch, on Easter Day, reads the Gospel in Greek, and it is then read by other persons (oi agioi archiereis) in various languages ("Typikon" for that day, ed. Athens, 1908, pp. 368, 372, Nilles, "Kal. man.", II, 314-15). The same thing is done again at the Hesperinos. The little Synopsis (Synopsis iera) of Constantinople (1883) gives this Gospel of the Hesperinos (John 20:19-25) in Greek (with two poetic versions, hexameter and iambic), Slavonic, Bulgarian, Albanian, Latin, Italian, French, English, Arabic, Turkish, and Armenian (all in Greek characters, pp. 634-78). The same custom is observed in Russia (Prince Max of Saxony, "Pr�lectiones de liturgiis orientalibus", Freiburg im Br., 1908, I, 116-17), where the Gospel of the Liturgy (John 1) is read in Slavonic, Hebrew, Greek, and Latin.
I don't know if any of that helps.
Peace & Joy,
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