4:6 sea of glass. See 15:2; Ex. 24:10. This imagery might suggest a number of associations. The parallel verse in 15:2 calls to mind the waters of the Red Sea. The defeat of Pharaoh and the pushing back of the waters foreshadowed God’s final victory over evil (Is. 51:9–11). If so, the sea of glass pictures waters subdued under God’s power. Moreover, the extent and beauty of the crystal-like sea, when taken together with the precious stones in v. 3 and 21:18–21, suggest the magnificence and preciousness of God’s throne. The numerous parallels elsewhere with the temple (4:2 note) might suggest that this sea is the heavenly counterpart of the sea in Solomon’s temple (1 Kin. 7:23–25). Finally, the picture of heavenly water might suggest that God faithfully supplies water from heaven (Deut. 11:11). It is consistent with the style of Revelation to weave together a number of Old Testament images.
four living creatures. These angelic ministers of God are reminiscent of the living creatures or cherubim of Ezek. 1 and 10 and the seraphim of Is. 6. They are guardians and bearers of the throne of God, as in Gen. 3:24; Ex. 25:17–22; Ps. 18:10; 1 Chr. 28:18.