The bread and the wine are not merely figures of the body and blood of Christ (God forbid!) but the deified body of the Lord itself: for the Lord has said, This is My body, not, this is a figure of My body: and My blood, not, a figure of My blood. And on a previous occasion He had said to the Jews, Unless you eat the flesh of the Son of Man and drink His blood, you have no life in you. For My flesh is meat indeed and My blood is drink indeed. And again, He that eats Me, shall live.Wherefore with all fear and a pure conscience and certain faith let us draw near and it will assuredly be to us as we believe, doubting nothing. Let us pay homage to it in all purity both of soul and body: for it is twofold. Let us draw near to it with an ardent desire, and with our hands held in the form of the cross let us receive the body of the Crucified One: and let us apply our eyes and lips and brows and partake of the divine coal, in order that the fire of the longing, that is in us, with the additional heat derived from the coal may utterly consume our sins and illumine our hearts, and that we may be inflamed and deified by the participation in the divine fire. Isaiah saw the coal....
[Damascene, De Fide. IV.13.] I've talked about the Isaiah passage in this context before; St. John is drawing on the traditional Liturgy of St. James, the oldest extant liturgical tradition of the East, which goes back in something like its current form to about the fourth century.
