Art of memory / mnemonics

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The art of memory — Latin ars memoriae — is the classical technique of remembering by places and images. The practitioner commits to memory an ordered set of locations, most traditionally the rooms of a building, and stations in each a vivid image standing for whatever must be recalled; walking the places again in imagination yields the material back in sequence. Antiquity credited the invention to the poet Simonides of Ceos. In the story Cicero tells in De Oratore, Simonides stepped out of a banquet in the house of the Thessalian noble Scopas shortly before the roof gave way and crushed the assembled guests beyond recognition; called upon to say who had died, he identified each mangled body for burial by recalling where its owner had reclined at table. From this, the tale concludes, he drew the principle of the whole art — that order of place is the backbone of recall, and that whoever would train the memory should fix in chosen places the images of the things to be held, so that the order of the places preserves the order of the matter. Whether a real Simonides ever made the inference is undecidable; the story is itself a mnemonic image, a founding scene built to be remembered.

The art of memory pictured as architecture: an imagined theater stage whose places hold the images to be recalled, from Robert Fludd’s Ars Memoriae (1619/1621) — Wellcome Collection, via Wikimedia Commons (CC-BY 4.0)

From the Roman schoolroom

As a documented practice the art belongs to Roman rhetoric, and it survives in three texts. The earliest and fullest is the anonymous Rhetorica ad Herennium of the first century BCE, which traveled for more than a millennium under Cicero’s name and so carried his authority into every medieval classroom; its third book gives the oldest surviving systematic account of memoria artificiosa, the “artificial” or trained memory set against the raw memoria naturalis. Cicero’s own De oratore treats memory as one of the five offices of the orator, and Quintilian’s Institutio oratoria, late in the first century CE, weighs the technique with a teacher’s mixture of respect and doubt. In all three the art is a working tool: the orator must hold a long argument, in order, without notes, and recover it on his feet before a court.

The Herennium lays out an architecture rather than a doctrine. One chooses loci — backgrounds, most often the parts of a building walked in a fixed order — that are distinct from one another, of moderate size, neither so bright that the images glare nor so dark that they vanish, and spaced at intervals that the inner eye can survey. Into these places one sets imagines, images for the things to be remembered, and the precept on images is the part that has fascinated every later reader: the mind passes over what is ordinary and common, but it fastens on the marvelous and the disgraceful, so the images should be active, striking, even grotesque — disfigured, comic, smeared with blood or paint, doing something — because the mind keeps what startles it. The places are reusable, like wax smoothed and written again; the images are discarded and renewed for each new speech. This is the entire mechanism, and in the Herennium it is offered with no metaphysics attached: a craft of the trained memory, no more occult than scales are to a musician. The Latin text and its careful Loeb translation are hosted on LacusCurtius, where the precepts can be read in their original setting among the duties of the orator; the Simonides scene that frames the whole tradition stands in Cicero’s De Oratore.

The architecture is portable across its later transformations, and it is worth marking the boundary at the outset: this is a discipline of construction, of building an ordered interior and furnishing it, and the description that follows gives the shape of that interior and the uses it was put to, not a set of steps to be performed.

The moralized memory of the Middle Ages

The Middle Ages received the art through the Herennium and turned it from a rhetorical convenience into a spiritual discipline. When Thomas Aquinas and his teacher Albertus Magnus, the great Dominican masters of the thirteenth century, took up the subject within scholasticism, they filed memoria not under rhetoric but under ethics: memory is a part of the virtue of prudentia, prudence, the cardinal virtue by which the soul holds the past in view in order to act rightly in the present. To remember well is then not a knack but a duty — a portion of the moral life. On this footing the trained memory became a devotional instrument, recommended for fixing in the soul the catalog it most needed to keep before it: the virtues and the vices, the four last things, the pains of hell and the rewards of heaven, the articles of faith arrayed so that none could slip from view. The grotesque image of the Herennium, once a schoolroom trick, now had work to do in the formation of conscience — the more violently a sin could be pictured, the more reliably it would be shunned.

The historian Mary Carruthers has shown how deep this went. Far from a marginal curiosity, the trained memory was, on her account, the medium in which much of medieval learning was carried and much of its writing composed: a monk did not merely store texts but built them into ordered interior structures — buildings, ladders, gardens, the rooms of an imagined Noah’s ark — through which meditation moved and out of which new composition came. The cathedral, the illuminated page, and the ordered memory belong to one habit of mind. The art was less a technique applied to thought than the architecture within which medieval thought happened.

The Renaissance turn: from device to cosmos

In the Renaissance the art acquired metaphysical ambitions, and the change of register is the hinge of its whole history. The places and images were no longer asked merely to hold knowledge in order; they were asked to mirror the order of reality itself, so that a memory built on the right plan would be not a storehouse but a model of the universe — and, on the boldest claims, a means of acting on it. The current that drew the art in this direction was the Hermetic and Neoplatonic revival set in motion when Marsilio Ficino translated the Corpus Hermeticum for Cosimo de’ Medici in 1463, founding the Renaissance reading of Hermes Trismegistus as the most ancient of sages and the prisca theologia it underwrote. In that climate, with Neoplatonism supplying a cosmos of descending images — the things below answering to the things above on the as-above-so-below principle — the inner images of the memory could be re-imagined as charged with the powers of the heavens whose forms they bore.

The first figure of Ramon Llull’s Ars Magna, a rotating combinatorial wheel of lettered principles whose machinery Bruno later fused with celestial images — after Ramon Llull, via Wikimedia Commons (Public Domain)

The most extravagant single project was the memory theater of the Venetian Giulio Camillo, on which he spent his life and a French king’s money. He inverted the ancient plan: where the Roman orator stood at the door and looked into his rooms, the spectator of Camillo’s theater stood where the stage should be and looked out at a wooden amphitheater of ranked images rising in seven grades, ordered under the seven planets, the whole claiming to lay out the principles of all things in a single view. The theater was partly built, much rumored, and never finished; its plan survives in L’idea del theatro, a treatise printed in 1550, after Camillo’s death. What it promised was no longer recall but comprehension — a place from which the furniture of the cosmos could be seen at once.

The more consequential figure is Giordano Bruno, the Nolan ex-Dominican who carried the art into open magic and infinite cosmology. His first surviving book, De umbris idearum (“On the Shadows of Ideas,” Paris, 1582), dedicated to Henri III — who, by Bruno’s own later testimony, had wanted to know whether his prodigious memory came by nature or by sorcery — sets images of the decans, the planets, and the fixed stars on revolving concentric wheels. The wheels are adapted from the combinatory art of the thirteenth-century Catalan Ramon Llull, whose combinatorial art had arranged the divine attributes on rotating figures so that turning them generated every true combination of terms. Bruno fused Llull’s logical machinery with celestial images: a memory whose contents were the forms of the heavens, mechanically recombined, would — on the claim — align the rememberer with the productive order of the cosmos, turning a mnemonic into something closer to an instrument of knowledge and power. The same continuity of images, bonds, and desire runs through his later magical manuscripts; for Bruno the art of memory, the theory of magic, and his infinite, centerless universe of innumerable worlds were facets of one project. The astronomical and metaphysical sides of that project are set out in the Stanford Encyclopedia of Philosophy’s account of Bruno, which treats the De umbris wheels alongside his cosmology rather than as a separate curiosity. This emblematic habit of mind — knowledge condensed into a charged image — is the same impulse that produced the Renaissance art of the emblem, where a picture, a motto, and an epigram together carry a meaning no plain statement could.

A revolving wheel from Giordano Bruno’s De umbris idearum (1582), setting images of the decans, planets, and fixed stars on concentric rings — after Giordano Bruno, via Wikimedia Commons (Public Domain)

The Yates reconstruction and its afterlife

The modern recovery of this whole arc is the work of one scholar above all. Frances Yates, of the Warburg Institute, reconstructed the line from Simonides to Bruno in The Art of Memory (1966), the companion to her Giordano Bruno and the Hermetic Tradition (1964). On her reading the Renaissance systems were no longer aids to eloquence at all: practitioners within the Hermetic current held that a memory organized by the cosmos’s own images would conform the mind to the universe and so transform it, mnemonics become a religious technique, the inner theater a means of grasping the divine. This was a striking claim, and it belongs to the larger and more contested Hermetic thesis Yates built across her career — that an occult, magical Hermeticism was a shaping force in early-modern thought, even a forerunner of the scientific revolution.

The monument to Giordano Bruno by Ettore Ferrari (1889) in the Campo de’ Fiori, Rome, where Bruno was executed in 1600; his memory wheels stand at the center of the Renaissance phase of the art — photograph by Jastrow, via Wikimedia Commons (Public Domain)

That larger thesis has been substantially revised. The genealogy on which the Renaissance art rested was itself an error of dating: in 1614 Isaac Casaubon demonstrated philologically that the Hermetic writings were not the work of an ancient Egyptian sage older than Moses but late-antique Greek compositions, a finding traced in Anthony Grafton’s study Protestant versus Prophet. Later historians — Robert Westman on Copernican astronomy, Brian Copenhaver on the philology of the Hermetica, Wouter Hanegraaff on the very category of a “Hermetic Tradition,” Hilary Gatti on Bruno as a serious cosmologist rather than a magus — have pruned the strong causal claim that Hermetic magic produced the new science, and have argued that what Yates read as a unified occult tradition was a more various and discontinuous reception of Hermes. Yet on this particular subject her work has worn best of all. The reconstruction of the ars memoriae — its passage from Roman rhetoric through Christian moralization to the Renaissance theaters and wheels of Camillo and Bruno — stands as broadly drawn, paralleled and anticipated by Paolo Rossi’s study of the combinatory tradition. What scholarship has qualified is the weight she put on the occult reading of the latest phase; what it confirms is the long shape of the development, from orator’s device to engine of universal knowledge. The two registers sit together without strain: the architecture of places and images is documented in plain Roman prose, while the cosmic claims attached to it in the sixteenth century are reported as the claims of the men who made them, neither endorsed nor explained away.

Research and primary texts

The classical foundation is the Rhetorica ad Herennium, Book III, the oldest extant account of the trained memory; Harry Caplan’s Loeb text and translation is hosted on LacusCurtius, with the memory section embedded among the duties of the orator. The Simonides story and the rhetorician’s framing of memory stand in Cicero’s De oratore, Book 2, in J. S. Watson’s nineteenth-century translation at attalus.org; Quintilian’s Institutio oratoria, Book 11, gives the third Roman witness, more skeptical of the art’s reach. For the long entanglement of memory, magic, and learned inquiry that frames the Renaissance phase, Lynn Thorndike’s A History of Magic and Experimental Science, whose first volume is in the public domain at Project Gutenberg, remains the great archival quarry, even where its flat “proto-empiricism” frame has been superseded. The modern scholarly arc runs through Frances Yates’s The Art of Memory (1966) and Paolo Rossi’s Clavis universalis (1960) for the combinatory and universalizing strand, and through Mary Carruthers’s The Book of Memory (1990) and The Craft of Thought (1998) for the medieval monastic practice, where the trained memory is shown to be the very medium of composition. Frances Yates’s books remain in copyright and are cited rather than reproduced; for the dating that pulled the metaphysical floor from under the Renaissance art, Grafton’s JWCI study of Casaubon is the standard treatment.

What endures

The technique itself proved robust across every change of register. The method of loci is taught in the same terms the Herennium used; competitive memorizers walk imagined palaces to recall the order of a shuffled deck; and experimental psychology, testing the claim directly, finds plainly that it works — that placing items in an ordered spatial scheme and re-walking it does improve recall. Through the rhetorical, the devotional, and the magical phases alike, one conviction held the whole long discipline together and grounded each of its uses: that the mind takes fast hold of what is placed and pictured, and that an ordered inner world answers to the order of the outer one.

→ Related: Emblematics · Infinite Cosmology Pluralism Of Worlds · Hermes Trismegistus · Neoplatonism · Cicero · Thomas Aquinas · Giordano Bruno · Ramon Llull · Lullism Combinatorial Art · Frances Yates · Marsilio Ficino · Renaissance Hermetism · Scholasticism · Middle Ages · As Above So Below · Corpus Hermeticum · Prisca Theologia