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 Jesus, that He may raise them up and save them. (CCC 1499) 

Illness and suffering have always been among the gravest problems confronted in human life. In illness, humans experience the powerlessness, the limitations, and the finitude. Illness can lead to anguish, self-absorption, sometimes even despair and revolt against God. On the other hand, it can also make human more mature, helping them discern in their life what is not essential so that they can turn toward that which is. Very often illness provokes a search for God and, hopefully, a return to Him. (CCC 1500, 1501) 

Christ’s compassion toward the sick and His many healings of every kind of infirmity are a resplendent sign of His love and mercy. Jesus has the power not only to heal, but also to forgive sins; He has come to heal the whole person, soul and body; He is the physician the sick need. His preferential love for the sick has not ceased through the centuries to draw the very special attention of Christians toward all those who suffer in body and soul. It is the source of tireless efforts to comfort them. (CCC 1503) 

“Heal the sick!” The Church has received this charge from the Lord and strives to carry it out by taking care of the sick as well as by accompanying them with her prayer of intercession. The Church believes in the life-giving presence of Christ, the physician of souls and bodies. This presence is particularly active through the sacraments, and in an altogether special way through the Eucharist, the bread that gives eternal life and that St. Paul suggests is connected with bodily health. However, the apostolic Church has its own rite for the sick, attested to by St. James: “Is any among you sick? Let him call for the presbyters of the Church and let them pray over him, anointing him with oil in the name of the Lord; and the prayer of faith will save the sick man, and the Lord will raise him up; and if he has committed sins, he will be forgiven.” Tradition has recognized in this rite one of the seven sacraments. The Church believes and confesses that among the seven sacraments there is one especially intended to strengthen those who are being tried by illness, the Anointing of the Sick. (CCC 1509-1511)