Text in English and German. The narrowest building in Cologne is the office of the advertising agency rendel & spitz. Once a year, during the 'Passagen', the offsite- programme of the international furniture fair in Cologne, the office is turned into an exhibition space: It serves as a stage for an installation of a chosen designer. In 2005 there was no exhibition. The accompanying book to the exhibition that never took place contained only empty pages. Just as in previous years, the book was sent out to designers, architects, artists, journalists and friends. One of the recipients then asked rendel & spitz whether he was supposed to fill the empty pages and sent the book back. An idea was born: each recipient was asked to lend his (used) book for the 2006 exhibition 'Dear Diary / Liebes Tagebuch'. The result is a collection of private notes, sketches, photographs, collages, and objects. The accompanying book shows a synopsis of the contributions, which in some cases are very personal. In addition to the book, there is a CD-ROM with the complete contents of each book that was contributed.