The Signs and the Rite of Confirmation

1293 In treating the rite of Confirmation, it is fitting to consider the sign of anointing and what it signifies and imprints: a spiritual seal. (695) Anointing, in Biblical and other ancient symbolism, is rich in meaning: oil is a sign of abundance and joy;¹⁰³ it cleanses (anointing before and after a bath) and limbers (the anointing of athletes and wrestlers); oil is a sign of healing, since it is soothing to bruises and wounds;¹⁰⁴ and it makes radiant with beauty, health, and strength.

1294 Anointing with oil has all these meanings in the sacramental life. The pre-baptismal anointing with the oil of catechumens signifies cleansing and strengthening; the anointing of the sick expresses healing and comfort. The post-baptismal anointing with sacred chrism in Confirmation and ordination is the sign of consecration. By Confirmation Christians, that is, those who are anointed, share more completely in the mission of Jesus Christ and the fullness of the Holy Spirit with which he is filled, so that their lives may give off “the aroma of Christ.”¹⁰⁵ (1152)

1295 By this anointing the confirmand receives the “mark,” the seal of the Holy Spirit. A seal is a symbol of a person, a sign of personal authority, or ownership of an object.¹⁰⁶ Hence soldiers were marked with their leader’s seal and slaves with their master’s. A seal authenticates a juridical act or document and occasionally makes it secret.¹⁰⁷ (698)

1296 Christ himself declared that he was marked with his Father’s seal.¹⁰⁸ Christians are also marked with a seal: “It is God who establishes us with you in Christ and has commissioned us; he has put his seal on us and given us his Spirit in our hearts as a guarantee.”¹⁰⁹ This seal of the Holy Spirit marks our total belonging to Christ, our enrollment in his service for ever, as well as the promise of divine protection in the great eschatological trial.¹¹⁰ (1121)

The Catechism of The Catholic Church , 2nd Ed., Ch. 1, Art. 2, Sec. 1293-1296;
Source: http://www.usccb.org/beliefs-and-teachings/what-we-believe/catechism/catechism-of-the-catholic-church/epub/