Even if Diderot and d’Alembert’s Encyclopedia is entitled Dic- tionnaire raisonné des sciences, des arts et des métiers, its ambition is to be much more than a dictionary. The encyclopedia has aimed since its genesis at being in continuous expansion in order to en- compass the ever-growing world of arts, sciences and techniques. The encyclopedia is not a series of buildings; it is a never-ending building site. [...] These two intellectual technologies have antagonistic functions. The Book has evolved as a closed space capable of hosting sophisticated inte- rior architecture: long discourses, elaborated narratives and other kinds of architectural thoughts that oral tradition used to transmit. On the contrary, the encyclopedia’s function is to encompass the whole world, past, present, future, real and imaginary. There will never be enough pages for such an unbounded commitment. The Book offers specific paths, guided tours. The Encyclopedia offers a small-scale model of the world. Book writing is about learning to finish. Encyclopedia writing is an ever-going activity aiming at con- tinuous improvement. When the technology was ready, the encyclopedia happily left its inappropriate body of printed volumes, to exploit the potential of hypertexts, the digital incarnation of principles it had already in- vented at the time of Diderot and d’Alembert in order to escape the imprisoning linearity imposed by the codex pages. [...] The network has successfully decomposed music albums into single songs, newspapers into sets of articles. Now it tries to decom- pose the courageous books that wander into its territory as collection of chapters, sets of linked fact-sheets, units of content in the World Wide Encyclopedia.