The Eucharist is a mystery because it is inexhaustible in both its intelligibility and reality. Why so? Because in the Eucharist we find that the divine and human meet, eternity and time meet, the infinite and finite meet, the divine will and human will meet, justice and mercy meet, grace and nature meet. Consider for example some of the many dimensions of the Eucharist:

• it is at once the re-presentation here and now of the Sacrifice of Christ that saves us from our sins;

• it is the food and drink of eternal life as it is the body, blood, soul and divinity of Christ;

• it’s the seed of our resurrection for we receive his glorified Body;

• it is the source of our transfiguration into being saints as adopted sons and daughters of God as the bread and wine is transubstantiated;

• it is the participation in the eternal life of the Trinity on this side of the grave;

• it makes us into the Body of Christ as the Church;

• it unites us to those in heaven, those in purgatory and those on earth in the Communion of the Saints who are present in the Mass with us etc...

Yet the Eucharist is also not just a profound and inexhaustible mystery it is also a necessity for mankind, if it is to be saved. As Jesus makes clear in these definitive words:

“Amen, Amen I say unto you: unless you eat the flesh of the Son of Man and drink his blood you will not have life in you.” [John 6:53]

“Those who eat my flesh and drink my blood have eternal life, and I will raise them up on the last day;” [John 6:54].

 It is for this reason that the Eucharist is the seed of the resurrection and why on our deathbed we are called to receive the Eucharist as Viaticum. Hence, why it is truly the Last Sacrament:

Code of Canon Law:

• Can.  921  §1. The Christian faithful who are in danger of death from any cause are to be nourished by holy communion in the form of Viaticum.

• Can.  922    Holy Viaticum for the sick is not to be delayed too long; those who have the care of souls are to be zealous and vigilant that the sick are nourished by Viaticum while fully conscious.

Catechism of the Catholic Church:

• CCC 1524 Communion in the body and blood of Christ, received at this moment of "passing over" to the Father, has a particular significance and importance. It is the seed of eternal life and the power of resurrection, according to the words of the Lord: "He who eats my flesh and drinks my blood has eternal life, and I will raise him up at the last day." The sacrament of Christ once dead and now risen, the Eucharist is here the sacrament of passing over from death to life, from this world to the Father.

• CCC 1525 Thus, just as the sacraments of Baptism, Confirmation and the Eucharist form a unity called "the sacraments of Christian initiation," so too it can be said that Penance, the Anointing of the Sick and the Eucharist as viaticum constitute at the end of Christian life "the sacraments that prepare for our heavenly homeland" or the sacraments that complete the earthly pilgrimage.