The apostle John is taken into the heavenly throne room and what a glorious scene it must have been! All of heaven singing praises to God on His throne. John can merely describe this heavenly vision with earthly terms.
The book of Revelation, the Apostle John's vivid record of Divinely revealed visions and messages, concerns the events surrounding the second coming of Christ. This illustration is taken from the scripture that actually describes that dramatic event in detail.