Adam Clarke on Revelation 20:7

Satan shall be loosed - How can this bear any kind of literal interpretation? Satan is bound a thousand years, and the earth is in peace; righteousness flourishes, and Jesus Christ alone reigns. This state of things may continue for ever if the imprisonment of Satan be continued. Satan, however, is loosed at the end of the thousand years, and goes out and deceives the nations, and peace is banished from the face of the earth, and a most dreadful war takes place, etc., etc. These can be only symbolical representations, utterly incapable of the sense generally put upon them.