The healing power of grace
By the sacred anointing of the sick and the prayer of the priests the whole Church commends those who are ill to the suffering and glorified Lord, that he may raise them up and save them. And indeed she exhorts them to contribute to the good of the People of God by freely uniting themselves to the Passion and death of Christ.
Illness and suffering have always been among the gravest problems confronted in human life. In illness, man experiences his powerlessness, his limitations, and his finitude. Every illness can make us glimpse death.
Illness can lead to anguish, self-absorption, sometimes even despair and revolt against God. It can also make a person more mature, helping him discern in his life what is not essential so that he can turn toward that which is. Very often illness provokes a search for God and a return to him.
The Anointing of the Sick is not a sacrament for those only who are at the point of death. Hence, as soon as anyone of the faithful begins to be in danger of death from sickness or old age, the fitting time for him to receive this sacrament has certainly already arrived.
The first grace of this sacrament is one of strengthening, peace and courage to overcome the difficulties that go with the condition of serious illness or the frailty of old age. This grace is a gift of the Holy Spirit, who renews trust and faith in God and strengthens against the temptations of the evil one, the temptation to discouragement and anguish in the face of death. This assistance from the Lord by the power of his Spirit is meant to lead the sick person to healing of the soul, but also of the body if such is God’s will. Furthermore, if he has committed sins, he will be forgiven.
In addition to the Anointing of the Sick, the Church offers those who are about to leave this life the Eucharist as viaticum. 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.
Source: Catechism of the Catholic Church (1499 – 1501, 1514, 1520, 1524)