He had never imagined so clearly the consequences of mailing a letter--the impossibility of retrieving it from the iron mouth of the box; the inevitability if its steady progress through the postal system; the passing from bag to bag and postman to postman until a lone man in a van pulls up to the door and pushes a small pile through the letterbox. It seemed suddenly horrible that one's words could not be taken back, one's thoughts allowed none of the remediation of speaking face to face.