Psalm 45 is a superb example of what C. S. Lewis has called “second meanings in the Psalms” (Reflections on the Psalms, 101–15). The primary meaning of the psalm is clear; it is a wedding song, celebrating the marriage of a king to a princess. In its original sense and context, it is not in any sense a messianic psalm. And yet within the context of early Christianity (and in Judaism before that), it becomes a messianic psalm par excellence. The express evidence for the transition is to be found in Heb 1:8–9, where Ps 45:7–8 is quoted with explicit reference to Jesus Christ. But the “second meaning” extends to the whole psalm, not merely to the two verses quoted, and it develops further the way in which the OT’s portrayal of human love and marriage may become the basis of an allegory of Christ and the Church, the Groom and the Bride.

PETER C. CRAIGIE AND MARVIN TATE, PSALMS 1-50, VOLUME 19: SECOND EDITION (WORD BIBLICAL COMMENTARY), 340.