The urge to record knowledge, understanding and natural phenomena in a coherent taxonomy has lain behind the compilation of encyclopedias and dictionaries over many centuries, from Isidore's late 6th-century Etymologiae and its medieval successors through to the opus of d'Alembert and Diderot (published 1751-1772) and subsequent works. The large size and wide scope of the resulting volumes have often elicited from both authors and readers the corresponding view that such reference works faithfully reflect, in some way or other, the world outside them. As the 17th-century educationalist Comenius wrote, 'Encyclopaedia is the system of all sciences, based on method and laid out like the world itself'.[1]