Historian Francis Yeats (1899-1981) conducted research into the Ancient art of visually organising, combining and retrieving knowledge at the Warburg Institute. This drawing is based on Yates’s 1952 reconstruction of the mnemonic wheel described in De Umbris Idearum [On the Shadows of Ideas] (1582) by the philosopher Giordano Bruno (1548-1600). It consists of six concentric circles divided into 150 rays each subdivided into 5 cells. Each circle contains words from a different category (such as agents, actions, attributes) and these can be learned and then combined by ‘turning’ the circles in your mind’s eye as a way to recall information. Bruno’s graphic scheme is a schematised map of the universe, intended to be committed to memory. Its six circles can function like clockwork rings in the mind’s eye that can be rotated to any combination.