The Church’s liturgical books describe the Mass as composed basically of two parts: the liturgy of the Word and the liturgy of the Eucharist. The liturgy of the Word includes the scriptural readings and psalm of the day, the homily, the profession of faith and the general intercession prayers. In liturgy, God’s word always has primacy, and so no liturgical action, whether it be the ordination of a bishop or something as simple as the blessing of a rosary, should take place without some form of proclamation of God’s word coming first. As an example, the Church’s official blessing for fishing gear begins with a suggested reading from Matthew’s gospel telling of the storm at sea in which Jesus is seen as the master of the winds and the waves. So the basic pattern of any liturgical act is this: God first speaks to us, then we make our human response.
The celebration of the eucharist in the earliest decades included a real supper, a similar structure to that of the Last Supper. Eventually, as the churches grew, this real supper became problematic, and was eventually abandoned. This left the participants with just the essentials of taking bread and wine, saying the blessing, and distributing Christ’s body and blood to all at table. This probably seemed too short a service to satisfy the religious feelings of the community. Consequently over time other elements were added to this basic eucharistic liturgy. These added elements would include the sharing of letters, communications, and greetings from neighboring communities, and especially from the founders of the community (the apostles or other missionaries). Also Jewish Christians would eventually stop attending synagogue services, but certainly the reading and preaching of God’s word that were central to synagogue services would help to shape the emerging liturgy of the word in the Christian Sunday liturgy.
From what historical records we have, we know that the earliest Christian liturgies of the word resembled those of the Jewish communities. St. Justin Martyr, for example, describes the liturgy as it was celebrated in the middle of the second century. He tells us that there were two readings, a sermon, and a closing prayer. Justin does not mention singing, but on this point we have unexpected evidence from a pagan witness, Pliny the Younger, governor of Bithynia, a Roman colony in Asia Minor. In a letter to his friend Emperor Trajan, he reports that he had sent an observer to see what Christians do at their Sunday liturgy. The observer reported that Christians are accustomed to gathering before dawn and begin by singing a hymn to Christ as their God.
The basic structure of the Mass and its liturgy of the word remain the same today. God first speaks the creative and saving word to us, then we utter our human response. The marvel, of course, is that God’s word is creative. Something wonderful always happens when God speaks. Isaiah explains it poetically in God’s words: “For as the rain and snow come down from heaven, and do not return there until they water the earth, making it bring forth and sprout, giving seed to the sower and bread to the eater, so shall my word be that goes out from my mouth; it shall not return to me empty, but it shall accomplish that which I intend, and succeed in the thing for which I sent it.”