(Gen. 9:12–16). Emanating from the throne are fearful sounds and sights (4:5) that recall God’s appearance in majesty at Sinai (Exod. 19:16–19). In front of the throne there is something that looks like an expanse of crystal-clear glass (4:6). In John’s day, ordinary glass would have been anything but clear; it was more like a sort of cloudy brown bottle-glass. Glass that was ‘clear as crystal’ would have been staggeringly expensive, so again this is an image of infinite value as well as stunning