GLASS, SEA OF (θάλασσα ὑαλίνη). In a description of heaven (Rev 4:6), before the throne of God is what seemed like a sea of glass, clear as crystal. Around it were gathered the beings who participated in worship before the Lamb opened the sealed book (ch. 5). Later, the sea appeared to be mingled with fire (Rev 15:2); appropriate to the judgments that were about to be poured out on the earth. Around the sea, the victorious saints sang the song of Moses and the Lamb, connecting this episode with the celebration of Israel’s victory over Egypt beside the Red Sea (Exod 15). The crystal sea fitly symbolizes the purity of God; the mingled fire speaks of His holiness inflamed by just wrath.