Giordano Bruno's third work on the Art of Memory or memory palace consists of a set of seals, which represent data structures for arranging and developing memory images and for processing mental representations and propositions. In this work, he fully combines for the first time both the retrospective Art of Memory and the prospective art of logic and judgment originally developed by Ramon Llull. Appended to this is the Seal of Seals, a discussion of psychological dynamics from a Neoplatonic viewpoint.