Our Sunday Visitor's Catholic Encyclopedia discusses the "Ancient of Days"; argues that it is a vision of God in bodily form ("theophany").
“Ancient of Days” in Our Sunday Visitor’s Catholic Encyclopedia, ed. Peter M. J. Stravinskas, rev. ed. (Huntington, Ind: Our Sunday Visitor, 1998), 69-70
Ancient of Days This divine title occurs in the Old Testament Book of Daniel. In the first of that book’s apocalyptic visions, the seer Daniel describes scene in which “thrones were placed and one that was ancient of days took his seat; his raiment was white as snow, and the hair of his head like pure wool; his throne was fiery flames, its wheels burning fire” (Dn 7:9). Daniel goes on to say that “with the clouds of heaven there came one like a son of man and he came to the Ancient of Days and was presented before him” (Dn 7:13).
The language of his theophany—a visual manifestation of God—draws on symbols and imagery common in ancient Israel and in the surrounding cultures, adapting them to serve as expressions of Israel’s faith. For example, the epithet “father of years” was applied to the Canaanite god ‘El. We find somewhat similar language in the Targum of Job found in Cave 11 at Qumran: “God is great, and his many days we do not know; the number of his years is endless.”