This article shows how concepts of knowledge that have periodically marked the history of encyclopedism can be illustrated by different geometric patterns. The most celebrated of these, the tree, marks the transition from the circular shape of the summa, the encyclion and other arenas for the expression of memory from Antiquity to the Middle Ages, to the web shape that emerged with Leibniz and culminated in explicit form in the Encyclopedia of Diderot and d’Alembert. It was through these successive organizational transformations and rearrangements that knowledge would break away from its classic constituent principles (unity, linearity, boundaries and hierarchies) into the freedom—well before the Internet—of an interactive space in which knowledge could circulate between the different sciences, aided by hypertext methods that readers could apply according to their centres of interest, by analogy or through associations of ideas that were provided for or not by a cross-referencing system.