However small it may be, the 10 x 15 centimetre space set aside for writing represents an unparalleled territory for experimentation - the situationists led by Guy Debord used it to send their insults to the most deserving. But strangely enough, they all mention rain or shine. The writer George Perec, always on the lookout for new literary forms, was amused by these stereotyped messages. With the members of the Ouvroir de littérature potentielle (Oulipo), a secret society of writers and mathematicians more akin to a hoax than a manifesto, he devised a system for writing 243 postcards by drawing randomly from 5 entries (location, considerations, satisfactions, mentions, greetings) combined with a triple choice from a table of 15 words (town, region, sunbathing, beach, siesta...).