Before we go any further, I'd like to share a URL with you that contains some information about liturgy. In fact, this is the starting point to get to the Divine Liturgy of St. Mark and the Divine Liturgy of St. James which we have mentioned but will not be discussing. The address is:
http://www.users.csbsju.edu/~eknuth/itr/ltgy/index.html
Having left our discussion with the end of the third century it's important to note that the basic shape of the Mass would not change at all in the future. The various elements were all pretty much present at this point. Certainly there would be many changes, but they did not affect the basic structure which, using our modern terms, can be looked at as the Liturgy of the Word and the Liturgy of the Eucharist. All Masses in the future would consist of some opening prayers, readings from Scripture, a homily/sermon, preparation of the gifts, the Eucharistic prayer/anaphora, communion and dismissal. Some elements would come and go during the period between 300 and 1997, others would remain virtually unchanged.
This period around the beginning of the fourth century also sees the beginning of concelebrated Masses. This normally happened when one bishop was visiting another and they chose to celebrate the Mass together. Eusebius records (second hand) a visit to Rome by Polycarp during the papacy of Anicetus. They apparently argued about something (not recorded) and settled the argument by presiding at Mass together (Polycarp must have been the principle celebrant because he confected the Eucharist).
Another change was taking place that would permanently affect the structure and format of the Mass. As the Church grew in size and importance, the house church no longer served the needs of the community. By the middle of the third century rich Christians were buying houses and outfitting them as churches (one example is found in Dura-Europas on the Euphrates). This was still too small, and the Church began to emulate the basilica model of public buildings found in Rome. These were easy to convert into liturgical spaces because they were long, regular and usually had a curved apse at one end. The community applied the Greek term "ecclesia" to the building just as they had earlier applied the term to the community of Christians. "Ecclesia" means "the community called out" and they saw these buildings as the place where the community could gather.
In general, the liturgy was celebrated in the vernacular and all the people participated under the bishop who was assisted by his priests. The deacons gave direction since the people stood and even milled about during the liturgy. Thus, the deacons cry of "Wisdom! Attend!" would precede a reading of the Gospel or a special portion of the Mass. The reason I say "generally" in the vernacular is because the Church was already celebrating bi- and tri-lingual liturgies! Egeria, a Spanish nun who wrote of her pilgrimage to Jerusalem, writes of a liturgy celebrated in Greek but with translation offered into both Syriac and Latin.
The changes in places of worship permitted another change -- the celebration of Mass on a daily basis. In the beginning Mass was celebrated only on Sundays, but now it was possible to celebrate the Mass any day of the week that was desired. This was never obligatory, and in fact during the episcopacy of Augustine Hippo never had daily Mass!
Thus, by the end of the fourth century we see the outline of what remains today: Mass in a special building reserved for that purpose, daily Mass, and another most important feature: Mass at which a priest is the presider. Up until this time the bishop was the normative presider at all Masses. However, the growing size of the Church and the increasing number of churches made it impossible for the bishop to attend each Mass. Thus the priest began to preside over the Mass. This involved a substantial increase in the number of priests. This meant that the most populous group of clerics, the deacons, were finally surpassed by the priests. In fact, this led to the eventual elimination of the diaconate as a permanent order until its restoration in 1970 as a result of Vatican II. I should quickly point out, however, that this elimination only took place in the West. The East continued to have permanent deacons throughout the history of the Church.
Although the basic structure of the Mass was universally the same there were minor variations which give rise to a rich tapestry reflecting the various practices and cultures.
The gathering rite (complete with entrance antiphon or song) already plays an important role in calling the community to worship. The came together as a community and with one voice joined in song. Arriving at the chair the bishop, or priest, would greet everyone in the name of Jesus saying "Peace be to you," or "Peace be to all," or even the popular "The Lord be with you," to which the universal reply was: "And with your Spirit" (or, as translated today, "And also with you.") St. Augustine describes the beginning of a Mass in Hippo following the cure of a young man afflicted with tremblings this way:
"We advanced toward the people. The church was full and resonated with cries of joy: Glory to God! Praise to God! No one was quiet, and the cries arose from all parts. I greeted the people who again cried out, redoubling their enthusiasm. When silence was finally restored, the readings of the Sacred Scriptures were proclaimed. When the moment came for em to speak, I said a few words related to the solemnity and to the joy which penetrated, leaving the faithful to admire the eloquence of God in the work which he had just accomplished rather than my discourse." (Augustine, The City of God 22.8.22)
Other elements of the structure of the church in those days would have seemed right at home today. The reader proclaimed the scripture from an elevated lectern. Surprisingly, the reader was frequently a child since a child's voice carried better in the basilica than did that of an adult! The deacon then, as now, read the Gospel. However, before he did so he would proclaim loudly, "Wisdom! Be attentive!" If there was seating in the Church he would insert the command to stand after the word "Wisdom!"
Following the readings the presider preached, frequently for an hour or more (just look at the length of some of St. John Chrysostom's sermons!) This was followed by the General Intercessions or Universal Prayer (which would disappear from the liturgy later on not to reappear until much, much later). The people then presented their gifts. This included the bread and wine, money and food stuffs for the clergy and the poor. The deacons would collect this (even the live chickens!) and then *they* would wash their hands before continuing (it wasn't until much later that the priest would adopt this necessary washing and turn it into a ritual washing!).
The Eucharistic prayer in the East took on a more Trinitarian aspect and they added the "epiclesis" or calling down of the Holy Spirit. This so influenced the East that, during the reforms of Vatican II, they complained that the Roman Canon had no epiclesis and, therefore, they wondered if it was even valid! Actually, there is an epiclesis, it's just misplaced (from the Eastern point of view). To give you a feel for this, here's the Epiclesis from the Byzantine Anaphora of St. Basil:
"Through the benevolence of your goodness, cause your Holy Spirit to come upon us and upon these gifts which we present to you, that he may bless them, sanctify them, and present to us in this bread the precious body and blood of Our Lord, God and Savior Jesus Christ, and in this cup the precious blood of Our Lord, God and Savior Jesus Christ, shed for the life of the world. And all of us who partake of the same bread and the same cup, unite us with one another in communion with the same Spirit. Cause that none of us partake in the sacred body and in the blood of your Christ unto judgment or condemnation, but so that we might find mercy and grace with all the saints that have been pleasing to you from the beginning of the ages."
Another tradition begins during this era. To symbolize the unity of the Church, the pope breaks a small piece of the consecrated bread and sends it to the other churches This is called the "fermentum" and we still see this action today, although now the fermentum is added to the chalice. Here's what Pope Innocent I, writing to Decentius, Bishop of Gubbio in 416 had to say:
"As to the 'fermentum' which we send on Sunday into the various titular churches, it is superfluous for you to consult us on this topic: here all the churches are built within the city. The priests of these churches, being unable to celebrate with us on this day because of the people entrusted to them, this receive from the acolytes the 'fermentum' confected by us so that they, especially on this day, do not feel separated from our communion."
Following the Eucharistic Prayer the people prayed the Lord's Prayer and then exchanged the Kiss of Peace. There were, however, variations on the time of the Kiss of Peace with most of the churches outside of Rome sharing it during the offertory. The thinking was along the lines of "Therefore, if you bring your gift to the altar, and there recall that your brother has anything against you, leave your gift there at the altar, go first and be reconciled with your brother, and them come and offer your gift" (Mt 5:23-24).
The bishop or presider received communion first, followed by the clergy and the laity. Normally a priest presented the bread and the deacon offered the cup. Here's what Ambrose says about receiving the Eucharist:
"So you say not indifferently 'Amen,' already confessing in spirit that you receive the body of Christ. Therefore, when you ask, the priest says to you: 'the body of Christ,' and you say: 'Amen,' that is, 'truly.' What the tongue confesses let the affection hold." (Ambrose, On the Sacraments, V.25) "If you are the Body of Christ and his members, you are the sacrament of what is placed on the table of the Lord; it is the sacrament of what you are when you receive. It is to what you are that you respond, 'Amen.' And this response is your signature. Be a member of the Body of Christ so that you Amen be true." (Ambrose, sermon 272)
As for how communion was received, Cyril of Jerusalem teaches this in his Mystagogical Catechesis V:21:
"So when you come, come forward, do not come with arm extended or fingers parted. Make your left hand a throne for your right, since your right hand is about to welcome a king. Cup your palm and receive in it Christ's body, saying in response Amen. Then carefully bless your eyes with a touch of the holy body, and consume it, being careful not to drop a particle of it. for to lose any of it is clearly like losing part of your own body. Tell me, if anyone gave you some gold dust, would you not keep it with the greatest care, ensuring that you did not lose by dropping any part of it? So you should surely take still greater care not to drop a fragment of what is more valuable than gold and precious stones. After partaking of Christ's body, go to receive the chalice of his blood..."
Finally, Mass concluded with the dismissal. In Rome the "Ite, missa est" begins to appear. It has no religious significance at first, and is akin to "the meeting is adjourned." In the East the dismissal is more frequently "Go in peace," preceded by some other prayer that differed from church to church. There was no closing song and the people left to discuss with each other what had happened.