After Warburg's death in October 1929 and the migration of the Institute to London in 1933, Brunian studies at the Warburg Institute took a very different direction thanks to the research of Frances Yates (1899-1981). While Warburg's interest in Bruno and image-based thinking brought his philosophy towards the present, Frances Yates' hypothesis of an Hermetic Bruno rooted his thought in a distant and partly mythical past at the antipodes of modern times. Nevertheless, while her Giordano Bruno and the Hermetic Tradition (1964) takes a different path from that traced by Warburg, her other Brunian study, The Art of Memory (1966), is perhaps her book closest to Warburg's preoccupations. Indeed the history of mnemonics practices, by means of which mythological figures lived from the Antiquity onwards as animated bearers of learning in the intimacy of the human brain, had everything to interest Warburg. In fact the Art of Memory was written in close consultation with Gertud Bing as confirmed by this excerpt from the preface:

Now that the Memory Book is at last ended, the memory of the late Gertrud Bing seems more poignantly present than ever. In the early days, she read and discussed my drafts, watching constantly over my progress, or lack of progress, encouraging and discouraging by turns, ever stimulating with her intense interest and vigilant criticism. She felt that the problems of the mental image, of the activation of images, of the grasp of reality through images – problems ever present in the history of the Art of Memory – were close to those which preoccupied Aby Warburg, whom I only knew through her.

Frances Yates expounded the first results of her research on Bruno's art of memory in a seminar at the Warburg Institute in 1952. She showed her reconstruction of the wheel described in the De Umbris Idearum, Bruno’s first mnemonic work published in Paris in 1582. The two wheels illustrated below are part of the same work and serve as an introduction to using the larger wheel.

In the first fixed ring the practitioner will assign a mythological or heroic figure to each letter. Bruno provides some examples : A Lycaon; B Deucalion; C Apollo; D Argos ... (see De Umbris Idearum, pp. 107 ff). The letters of the second ring correspond to an action or a scene associated with each figureThe examples provided are: AA Lycaon at a banquet; BB Deucalion and pebbles; CC Apollo and Python; DD Argos and some cattle (ibid, p. 112). Thus rotating the first inner ring operates permutations between the figures and their action. Further permutation occurs when the third wheel is set in motion. It contains attributes or enseignes which can be easily passed from one figure to another. Bruno provides only four examples and leaves the rest to the imagination of his reader. These are : AAA, Lycaon at a banquet with a chain; BBB, Deucalion and pebbles with a headband; CCC, Apollo and Python with a baldric; DDD, Argos and some cattle with a hood. This way the systems makes it possible to create combinations of letters representing words, acronyms or syllables to be remembered by means of animated images mixing the attributes and accustomed actions of familiar mythological figures.

BAA: B Deucalion A at a banquet A with a chain 
MAD: M Perseus A at a banquet D with a hood
CAD: C Apollo A at a banquet D with a hood
COD: C Apollo O and Proserpina D with a hood

To approach the larger wheel Bruno advises his reader that ` is necessary to dilute the printed page into an immense space'. The last section of De Umbris idearum describes the content of  the larger wheel over 40 pages. It consists of five concentric rings divided into 150 rays each subdivided in 5 cells. On the outer rings are numbers, letters, the name of inventors followed by four more wheels of words corresponding to the categories of agent, action, enseignes, attributes (adstans) and circumstance.

Frances Yates reconstruction of Giordano Bruno memory wheel from 'De Umbris Idearum'

`How did the system work? By magic of course, by being based on the central power station of the … images of the stars, closer to reality than the images of things of the sublunar world, transmitter of the astral forces, the `shadows’ intermediary between the ideal world above the stars and the objects and events in the lower world.’ (The Art of Memory, p. 223)

This interpretation, based on a misplacing of the images of the planets, was first revised by Rita Sturlese in her critical edition of the De Umbris  of 1991 (pp. LXVIII ff.) and later by Francesco Torchia (‘La chiave delle ombre’, Intersezioni, 1, 1997, pp. 131-151). Both scholars strip Bruno’s construction of its magical character. According to Sturlese the wheel is in fact an adult toy conceived to learn foreign words. Here each ray corresponds to a set of syllables combining one consonant with one vowel. Thus reconstructing a word with its phonetic constituents amounts to combining the various elements of each section. The addition of the images described in the last ring before the hub creates in the end a mnemonic background by means of which new words can be remembered. For instance to remember the word Numeratore you should pick the first syllable in the outer ring, NU, which corresponds to `Apis’; the second syllable in the second ring, ME: `in tapeta ’; the third syllable, RA, in the third ring: `deploratus’; the fourth syllable, TO, from the 4th ring: `compedes’; and finally RE in the 5th ring. This last ring  provides a background against which to set the image thus created:  `…mulier super hydram tres cervices e quarum singulis septem exiliunt capita habentem, vacuas antrorsum tendens manus’ (De Umbris, p. 151).

Thus you can remember the word numeratore through the following image composed by the combinatory wheel:`the god Apis weaving a rug and wearing rags with wood blocks on his feet, with, in the background, a woman stretching out her hands and riding an hydra with many heads.’

Torchia's objections to this system are too long to be listed here. His main point, following the traditional criticism of classical mnemonics, is that it requires far more cognitive effort to memorise the images than the words themselves. His observation that the figures placed on the outer ring of the wheel represent all the inventors of all the arts suggests that Bruno's object could serve as a means of discoursing on and memorising any subject, very much in the spirit of Giulio Camillo del Minio's memory theater (ibid. p. 146). This interpretation places a central importance on the images of the planets. The practitioner of the art will himself select the agent and the actions for memorising an argument and associate his selection with the astral image corresponding to the figure of inventors selected on the first outer ring (see Torchia p. 148). In this interpretation the image composed is associated with a narrative, now embedded in the astral figure.

Such object can in fact be put to many uses. To the sources used by Bruno and listed by Mino Gabriele (Giordano Bruno: Corpus Iconographicum, pp. 36-40) could be added Leon Battista Alberti's ingenious system, expounded in his book on ciphers, by which wheels very similar in appearance to those illustrated in the De Umbris Idearum serve the purpose of coding and decoding messages - a method that can be applied to Bruno's mnemonic system. Thus while Frances Yates's earlier reconstruction is not completely accurate, and her assumption that the wheel worked by magic as an inner talisman is no longer tenable, it still offers a useful visualisation of the complex and powerful system Bruno had in mind

Scholarship has greeted Yates's views on Bruno and Hermeticism with considerable scepticism while less specialised literature continues to repeat her findings thanks undoubtedly to the greater diffusion of English language literature as much as to the outstanding clarity of her style. She nevertheless remains one of the first English speaking scholars to have highlighted the importance of early modern mnemonics. Writing in the early 60s, and criticised for detaching the past from Modernity, she could not anticipate that the art of memory would experience a true renaissance. Today thanks to recent technology a single individual can carry several thousands of texts, sounds and images in a container smaller than a pack of cigarettes and access them through a screen. Thus Frances Yates's studies on the survival of the Ancient art of visually organising, combining and retrieving knowledge may now be apprehended as early modern solutions to eminently contemporary problems.

François Quiviger