Against this background of an absolute Encyclopaedia, human beings constitute intermediary forms of a composite and limited universality: alphabetical encyclopaedias, which accommodate the greatest possible quantity of learning in the arbitrary order provided by letters; pasigraphies, which make it possible to transcribe all the languages of the world by means of a single system of figures; polyvalent lexicons, which establish synonymies between a greater or lesser number of languages; and, finally, rational encyclopaedias, which claim to 'exhibit as far as is possible the order and concatenation of human learning' by examining 'their genealogy and their filiation, the causes that must have given rise to them and the characteristics that distinguish them'.