To plug up as many steganographic channels of communication as possible, the Office of Censorship banned in advance the sending of whole classes of objects or kinds of messages. International chess games by mail were stopped. Crossword puzzles were extracted from letters, for the examiners did not have time to solve them to see if they concealed a secret message, and so were newspaper clippings, which might have spelled out messages by dotting successive letters with secret ink-a modern version of a system described more than 2,000 years earlier by Aeneas the Tactician. Listing of students’ grades was tabooed. One letter containing knitting instructions was held up long enough for an examiner to knit a sweater to see if the given sequence of knit two and cast off contained a hidden message like that of Madame Defarge, who knitted into her “shrouds” the names of further enemies of the French Republic, “whose lives the guillotine then surely swallowed up.” Childish scrawls, sent from proud parents to proud grandparents, were removed because of the possibility of their covering a map. Even lovers’ X’s, meant as kisses, were heartlessly deleted if censors thought they might be a code.