Schmemann tells us that the Eucharist is first of all a state of existence. "Eucharist, thanksgiving, is the state of the innocent man, the state of paradise. Before sin, man's life was eucharistic, for 'eucharist' is the only relationship between God and man which transcends and transforms man's created condition" (Liturgy and Tradition, p. 111). "Eucharist", therefore, is a state of being, a state of complete dependence lived as "love, thanksgiving, adoration", and this is true innocence and freedom.
Original sin, he goes on, was "the loss of that eucharistic state", of the blissfully real life we had in love and communion with God. The Old Testament is a record of failed attempts to recover this eucharistic state. In the end, of course, it was restored to us in Christ. "His whole life, and he himself, was a perfect Eucharist, a full and perfect offering to God. Thus the Eucharist was restored to man."
This is what happens in the Mass, as Schmemann tells us in his exposition of the Church's mystagogy. It happens because the Mass (the Divine Liturgy) places us in the "eighth day", the eschaton. It does not just place us in the past, by making us present at the Last Supper or at the foot of the Cross. It cannot, because those events themselves project us into the eschaton, into the state of glory which is the life of the Holy Trinity, in the presence of the holy Angels (invoked in the Sanctus).
Schmemann was quite concerned that the richly symbolic, or allegorical, accounts of the meaning of the Byzantine Liturgy that developed after the first few centuries tend to bear little relation to what actually goes on in the liturgy, as though they were being "read into" it, rather than unfolded from it. In order to get back to a more authentic mystagogy, one has to look at what is actually said and done in the liturgy, and this, he thought, could best be understood in terms of eschatological symbolism. The words and actions performed by the priest and people reflect the very heart of the early Christian experience of the Church as a "passing over" into Christ's kingdom, in order then to bear witness to it in the world.
This authentic early Christian experience of the liturgy is reflected above all in the Book of Revelation, as I indicate in All Things Made New, and we can recapture this experience by attending properly to the Mass and making it our own – by "participating" in the action of the liturgy. As the Roman Canon puts it, the holy victim is "borne by the hands of your holy Angel to your altar on high in the sight of your divine majesty, so that all of us, who through this participation at the altar receive the most holy Body and Blood of your Son, may be filled with every grace and heavenly blessing."
Detail of the Ghent Altarpiece from Wikipedia.