I am a huge proponent of progressive music, in all shapes and sizes. But what exactly is progressive music. Well… there are the flag bearers in Rush and Yes. There are the soothing sounds of Stephen Wilson and Porcupine Tree. There are the heavier visions of Devin Townsend or Dream Theater. Some have called System of a Down progressive. There is Tool, The Mars Volta, ISIS…Marillion, hell even Metallica has tromped into the progressive realm…. But it’s hard to hit what exactly that term means.