Fr Divo Barsotti (The Eucharist in St Paul of the Cross) p21ff suggests several things as St Paul’s original contributions to the theology of the Mass. He notes the following items:
A. The soul is a living tabernacle for Jesus because it makes present his death and resurrection.
Even if the saint never explicitly affirms it, we could say that communion realizes the transformation of the believer into him who is so received that the mystical experience would be none other than the ever more conscious and profound insertion into the Mystery, the participation of the Christian in the death and resurrection of Jesus. By eucharistic communion the soul becomes a living tabernacle of Jesus, because Jesus lives in him and makes present in him his death and resurrection. . . .
The “mysticism of the Passion” is the transformation of the believer into the crucified and risen Christ; not contemplation as the act which one performs, but the grace of the Sacrament which takes one into the Unity of the Mystery
2. A second item under the “originality” of St Paul, according to this study by Barsotti.: In St Paul of the Cross, death never transcends nor is it ever separated from the resurrection. (p. 22)
. . . The soul of Paul lives the mystery of the death in the solitude and silence of Jesus in the Host.
3. Participation in the unity and totality of the mystery.
For him Christianity is not an adventure, a journey towards an uncharted future, not even a return to the font, but an insertion into a living Presence, who is the definitive Reality of everything.. . . As secret heart of the world, Christ draws the faithful to himself in death, but for a new birth in God. . . . The preaching of the Cross and the mysticism of the Passion are thus the proclamation itself of salvation, which the individual already experiences and lives by withdrawing himself from the world of dispersion and sin. Before compassion is an asceticism and a psychological experience, it is an ontological participation in the Mystery. The presence of the dead and risen Christ in the Mystery becomes fully real in the Christian at the moment that Christ becomes present for communion. Thus Eucharist makes the Church; Eucharist makes the Christian and the saint.
If Paul seems to prefer Holy Communion among the aspects of the Mystery of the Eucharist, it is because in communion the presence of Christ becomes intimate and complete in the person who receives him and this prese3nce makes him with Christ one sole sacrifice, one sole holocaust.
Barsotti concludes that the mysticism of St Paul of the Cross especially recognizes the centrality of the Paschal Mystery.
Barsotti concludes his study (p.26):
The mysticism of St Paul of the Cross not only recognizes the centrality of Christ, but more especially the centrality of the Paschal Mystery. The mediation of Christ is realized in the presence of that same Mystery in which death and resurrection become complementary aspects of one sole life that excludes the possibility of death and communicates God’s glory to man.source