Poetry is, first and last, language - the rest is filler.
I believe that all poetry is formal in that it exists within limits, limits that are either inherited by tradition or limits that language itself imposes.
...In another time, What cannot be seen will define us, and we shall be prompted To say that language is error, and all things are wronged By representation. The self, we shall say, can never be Seen with a disguise, and never be seen without one.
