The Eucharist is rooted in the Last Supper and Jesus' command to do this in His memory. Because the Last Supper was the last time Jesus celebrated Passover with his disciples, the Eucharist has strong Jewish roots.
The simplicity of the celebration in the early Church, consisting of the telling of the story and the blessing of the bread and wine, was adapted to meet the needs of the local communities and throughout time, has become more ritualized.
The symbolic thinking about the Eucharist turned into a more mechanical or instrumental type of thinking, which was characteristic of the medieval Church. It became less important "why" Jesus gave us the Eucharist than "how" the bread becomes His Body and the wine becomes His Blood.
Additionally, the symbolic understanding also gave way to a literal understanding of the way that Christ is present in the Eucharistic Bread and Wine. This resulted in a decreased level of participation, less frequent reception of the Eucharist and a greater devotion to the Blessed Sacrament outside of Mass. This trend is reflected in the ritual and architecture, which became more complex and grandiose.
In light of the second Vatican Council, there was a major return to the original theology and celebration of the Eucharist. Today's celebration is characterized by full, conscious and active participation of the entire assembly. The emphasis on the presence of Christ has shifted away the Eucharistic Bread and Wine only, to include the assembly, the priest and the Word.
The Eucharist, from the Greek "Eucharistein, to give thanks," is the sacramental celebration of the Paschal Mystery. The Eucharist consists of the Liturgy of the Word and the Liturgy of the table. During the former, the community tells the story of salvation as it has been revealed in the life, death and resurrection of Jesus Christ. During the latter, the community celebrates Jesus' sacrifice for the life of the world.