In the Book of Revelation, St. John recounts a vision of heaven God had given him. In that vision, he sees a great throne covered in precious stones and surrounded by an emerald-like halo, with a sea of glass laid out before it. He hears a trumpetlike voice and peals of thunder. Twenty-four elders, all on their own thrones, cast golden crowns before the Lord as they worship him (Revelation 4:1-11).