Christ in Both Testaments

Hebrews 1:3 Who being the brightness of [his] glory, and the express image of his person, and upholding all things by the word of his power, when he had by himself purged our sins, sat down on the right hand of the Majesty on high;

Christ as manifested to the patriarchs, as symbolized in the sacrificial service, as portrayed in the law, and as revealed by the prophets, is the riches of the Old Testament. Christ in His life, His death, and His resurrection, Christ as He is manifested by the Holy Spirit, is the treasure of the New Testament. Our Saviour, the outshining of the Father's glory, is both the Old and the New.
{COL 126.3}