Tertullian, On Baptism 7
After leaving the baptismal bath, we receive a blessed anointing that comes from an ancient practice: in the old days, priests were anointed with oil from a horn. That custom goes back to Aaron, whom Moses anointed. The very name 'Christ' comes from 'chrism,' meaning anointing — the title fits the Lord because He was anointed spiritually, by the Spirit from God the Father, just as Acts says: 'They were truly gathered together in this city against Your holy Son, whom You anointed' (Acts 4:27). In us, too, the anointing is applied physically, but its benefit is spiritual — exactly like baptism itself: the bodily act is immersion in water; the spiritual effect is freedom from sins.
Latin
Exinde, egressi de lavacro, perungimur benedicta unctione de pristina disciplina, qua ungi oleo de cornu in sacerdotium solebant. Ex quo Aaron a Moyse unctus est: unde Christus dicitur, a chrismate quod est unctio, quae Domino nomen accommodavit, facta spiritualis, quia spiritu unctus est a Deo Patre, sicut in Actis: Collecti sunt enim vere in ista civitate adversus sanctum Filium tuum, quem unxisti. Sic et in nobis carnaliter currit unctio, sed spiritaliter proficit: quomodo et ipsius Baptismi carnalis actus, quod in aqua mergimur; spiritalis effectus, quod delictis liberamur.