Holy Chrism is sacred anointing oil consisting of balsam and olive oil, and blessed by a bishop in apostolic succession. According to the Eastern and Western Church Fathers and the medieval writers, the use of Holy Chrism was instituted by the Twelve Apostles.

Holy Chrism is employed in the sacraments of Baptism, Confirmation, and Holy Orders. It was also sometimes employed in medieval coronation ceremonies.

In discussing Holy Chrism in his Summa theologiae, St. Thomas Aquinas cites Pseudo-Dionysius two times. (Although, I believe that Dionysius of Acts 17 did not write the Corpus Areopagiticum, I hate prefixing the Areopagite with “pseudo”. We all know who we are talking about here.)

Here is how Aquinas uses Dionysius. Both citations are found in STh III, q. 72:

However, the apostles commonly made use of chrism in bestowing the sacrament, when such like visible signs were lacking. For Dionysius says (Eccl. Hier. iv): “There is a certain perfecting operation which our guides,” i.e. the apostles, “call the sacrifice of Chrism.” (STh III, q. 72, a. 2, ad. 1)

And then, they used both matter and form according to Christ’s command. For the apostles, in conferring the sacraments, observed many things which are not handed down in those Scriptures that are in general use. Hence Dionysius says at the end of his treatise on the Ecclesiastical Hierarchy (chap. vii): “It is not allowed to explain in writing the prayers which are used in the sacraments, and to publish their mystical meaning, or the power which, coming from God, gives them their efficacy; we learn these things by holy tradition without any display,” i.e. secretly. (STh III, q. 72, a. 4, ad. 1)

If we go back and read the passages in The Ecclesiastical Hierarchy of Dionysius, we observe that Dionysius understands “Chrism” itself as a sacrament proper. It seems that Confirmation and Holy Orders fall under this sacrament of Chrism, as well as the consecration of altars.

Given the importance on Christ as the Anointed, the institution of a kind of sacred chrism in Exodus 30, and the ancient usage of chrism in baptismal liturgies, it would seem that the institution of Sacred Chrism is apostolic. The apostolic origin of chrism has been controversial. Although the New Testament doesn’t mention chrism per se, there does seem to be allusions to Christians having received an “anointing”. See 1 John 2:20-27. Also, Revelation 3:18 connects anointing to wearing white robes.