Paris Review editors report that they received an unsolicited essay from the late founder George Plimpton about his first-hand experiences as a ghost Tuesday. 'I have always believed in immersing myself in my investigative work, be it as an acrobat, a boxer, or a Detroit Lion,' read the cover letter accompanying the 3,200-word essay that materialized in the current editor's mailbox Monday. 'Dying two years ago afforded me the unique opportunity to examine the afterlife from both sides of the Pearly Gates.' Plimpton's letter said he would waive all payment, as he no longer has any use for things of the mortal world. 