How Humans Used Their Hands to Remember Everything
From The Observatory
Source: Public Domain Review
From Buddhist monks to Renaissance musicians, fingers and palms once served as portable, visual, and kinesthetic tools for storing knowledge.
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No one knows who made a particular drawing of an 8th-century monk, perhaps a member of an esoteric Buddhist cult traveling the Silk Road. Nonetheless, the piece sat long forgotten in a walled-off library in China’s Mogao Caves. When the library was uncovered in 1900, the drawing—lifted from a trove of religious manuscripts—had aged well. Its subject is timeless, showing a pair of human hands.
The hands are disembodied, perched on lotus petals, with the palms facing the viewer. Their fingers, vigorous and elegant, are annotated with Chinese characters: The lowest tier of characters on the tips names each digit; above that, a second row gives the five Buddhist elements (space, wind, fire, water, and earth); and a final tier, floating upwards as if on kite strings, lists the 10 virtues, among them meditation, effort, charity, wisdom, and patience. The drawing illustrates a mnemonic system as a way of projecting knowledge onto the hands so that it can be studied, memorized, and stashed in a pocket.
Around the same time as the creation of this mnemonic, another monk named Bede, who lived in a Northumbrian monastery halfway around the world, was developing a different system of manual knowledge. In 725, he published The Reckoning of Time, a treatise in which he laid out a method for determining when Easter would fall on any given year, alongside discussions of shadows, moonlight, and the solstices. This may sound like a trivial exercise, but for Christians at the time, it could hardly have presented a more important or vexing problem.
The date of Easter falls after the spring equinox in the Northern Hemisphere, on the Sunday immediately following the first full moon. To find this date, one needs to reckon with planetary rhythms, which Bede mapped across his hands. He observed that the five fingers contain 14 joints, plus five nails—19 landmarks in all. This number tracks the metonic cycle, or the number of years it takes for the moon to return to the same phase on the same calendrical day. Minus the nails, the joints of both hands taken together give you 28 landmarks, representing the approximate length in years of a full solar cycle. Bede noted that in this way, the hands can “readily hold the cycles of both planets.” Beyond this basic setup, he left the details obscure and did not include an illustration, a technique of which Bede wrote, “better conveyed by the utterance of a living voice than by the labor of an inscribing pen”. Nevertheless, his system of computus digitorum (or simply computus) found an appreciative audience, who widely circulated and adapted it, making it a cornerstone of Christian learning for centuries.
These two systems are perhaps the earliest examples of manual mnemonics that come down to us only in outline, yet we have little trouble recognizing their appeal. They seem to spring from an impulse that transcends time and place as a deeply human drive to reach for props to help us reason and remember. “When thought overwhelms the mind,” psychologist Barbara Tversky wrote, “the mind puts it into the world.” In the case of hand mnemonics, we put those thoughts out into the world, in a sense, but also keep them within easy reach.
In the beginning, the hand was just a hand … or so we can imagine. It was a workaday organ, albeit a versatile tool for grasping, holding, throwing, and hefting. Then, sometime millions of years later, the hand took on other duties as an instrument of mental labor beyond one of menial means. As a species, our systems of understanding, belief, and myth have grown more elaborate and cognitively overwhelming. Thus, we started to put those systems out into the world to tally, track, and record by carving notches into bone, tying knots in string, spreading pigment on cave walls, and aligning rocks with celestial bodies. Of course, hands abetted these early mental labors, but they would later become more than mere accessories: Beginning approximately 1,200 years ago, we started using the hand itself as a portable repository of knowledge—namely, a place to store whatever tended to slip our mental grasp. The topography of the palm and fingers became invisibly inscribed with information of all kinds, ranging from tenets and dates to names and sounds. The hand proved itself versatile in a new way as an all-purpose memory machine.
The arts of memory are well known, but the role that the hand plays is often overlooked. Beginning with the 20th-century pioneering work of Frances Yates, Western scholars began piecing together a rich tradition of mnemonic practices that originated in antiquity and later took hold in Europe, with the most celebrated of these being the “memory palace.” Using this technique, skilled practitioners can memorize vast collections of facts by nesting them in familiar places (or “loci”), the chambers of a building or along a well-known route (to make these places more memorable, a bizarre image is often added to each one…the more jarring, the better). It is an odd omission that hand mnemonics are rarely mentioned alongside memory palaces. Both techniques are powerful and broadly attested. Both are adaptable, able to accommodate whatever type of information one wants to remember. And, both work along similar principles, pinning to-be-remembered items to familiar locations.
The two traditions do have significant differences, however. Memory palaces exist solely in the imagination, whereas hand mnemonics exist half in the mind and half in the flesh. Their intended use differs, with memory palaces being idiosyncratic in nature, tailored to the quirks of personal experience and association, and used for private purposes; they are very much the province of an individual. By contrast, hand mnemonics are the province of a community as a tool for collective understanding, offering a way of fixing and transmitting a shared system of knowledge and serving private purposes, such as contemplation as seen in the case of the Mogao mnemonic or calculation in the case of Bede’s computus. But, hand mnemonics also have powerful social functions in teaching, ritual, and communication.
The richness of this overlooked tradition is glimpsed through its ubiquity. In medieval Europe, Christian hand mnemonics were commonplace, with several echoing the Mogao system in appending key teachings to manual loci. A 1466 woodcut from Germany titled “The Hand as the Mirror of Salvation” assigns a different spiritual stage to each finger: God’s will to the thumb, examination to the index, repentance goes to the middle, confession is pinned to the ring, and the pinkie gets satisfaction. Also from Germany, a 1491 devotional treatise offers readers a “digital” table of contents highlighting how the book’s 100 meditations are distributed across the hands. Another illustration in the same work populates the hands with miniature portraits of key Christian figures, in which apostles and saints gaze out from each of the 12 major divisions of the four fingers (Mary and Jesus share the thumb).
At different times and places, hands also served as mnemonic maps of sound. The so-called “Guidonian hand” owes its name to the 11th-century Italian music teacher and scholar, Guido d’Arezzo. Arranging the different pitches in a scale onto the joints, he developed this technique to help students learn “unheard melody most easily and correctly.” Oddly, Guido’s own writings never depict the hands explicitly, but history nonetheless credits him, and for centuries after his death, the Guidonian hand was a mainstay of musical instruction. One scholar has described it as “fundamental conceptual equipment” for all musicians of the time.
Perhaps inspired by Guido, other European thinkers developed systems for learning the sounds of language. In the 1400s, the writer John Holt devised a hand-based technique for memorizing the Latin declensions, and in 1511, the German scholar Thomas Murner proposed a hand mnemonic for parsing German speech. However, these authors were a few centuries behind their counterparts in China, where the hand had long figured in phonology. Often called “rime tables,” Chinese scholars projected syllable charts onto the palms and fingers from as early as the 13th century. This can be seen in a 1600s version, which maps 32 key sounds across the fingers (16 to each hand). In Europe, several mnemonics that sprang from the rootstock of Bede’s system used the hand to reckon time. A remarkable example comes from a 1582 volume of practical astronomy by Jehan Tabourot, a French polymath best known for his work on dance, who published under an anagrammatic pen name, Thoinot Arbeau. The volume is a slim 61 pages, of which 11 include images of hands presented in various configurations, layered with different kinds of data. Among these is a mnemonic for keeping track of a notorious calendrical quirk comprising the alternation of long and short months. The image shows a left hand, with the thumb, middle, and pinkie fingers extended; meanwhile, the index and ring fingers are curled back toward the palm. The system begins with March, pegged to the extended thumb (31 days); then proceeds rightward to April on the curled-in index finger (30 days); then to May on the extended middle finger (31 days); and so on. It continues by traversing the five fingers twice, ending with January (31 days) on the thumb and February (28 days) on the index.
One of the most ambitious of all hand mnemonics was not tailored for time, sound, or any one type of information. Presented by Girolamo Marafioti of Calabria in a 1602 treatise on the arts of memory, the system consists of a map of 92 manual loci (23 on the front and back of both hands), each housing a different geometric symbol, such as a crescent moon, a chalice, a circle with horns, and even one that looks like a lemon. To use the system, one simply assigns a to-be-remembered tidbit to each locus, which Marafioti suggests could be used to remember a group of people arranged by status, age, or other characteristics. The system compresses the features of a memory palace—the use of familiar terrain and distinctive images, its customizability—into a handy pocket-sized device.
A global survey of hand mnemonics includes Jewish hand-calendars that resemble Bede’s computus, the hand-based techniques (of which mariners used to track moon and tide, an elaborate manual system for remembering key moments in Dutch history), the mnemonic alphabet from 1579 (in which different hand shapes represent different letters), and a variegated vein of Chinese medical mnemonics. A truly comprehensive treatment would also survey the borderlands of this tradition, in which, in some cases, the hand is mentally inscribed with information, but the primary function does not seem to be as a memory aid. Examples include alphabets used for communication with the deaf that relied on manual loci, hand-charts studied by practitioners of chiromancy and the Kabbalah, systems for converting the hand into a sundial, and bodily maps used for divination and exorcism. In the last case, for instance, a 1152 Chinese illustration invites readers to press on various parts of the hand (called mu or “eyes”) to dispel different kinds of evil.
Spending time amid this rich tradition raises questions. First, what makes the hand so popular as a mnemonic prop? A large part of the answer certainly involves portability, given that the hands are always, well, ready to hand. Another part is familiarity: Though popular wisdom stresses how well we know the back of our hand, the palm is hardly terra incognita. A further advantage is that hand mnemonics offer both visual and kinesthetic routes to memory, as they are both seen and felt. And, a final part of the answer is that the human hand can be parsed and construed variously. Seen one way, we have perfect housing for 10 virtues. Yet, seen another way, we have a fitting framework for 12 apostles, 32 syllables, or 100 meditations.
But why did hand mnemonics emerge when they did? What niche did they fill? The examples considered here suggest the tradition flourished in a period when literate and oral cultures coexisted, a time when some (the scholarly elites) were developing complex systems of knowledge in monasteries and universities, while others (the broader public) were trying to master those systems and use them in everyday life. Hand mnemonics may have been perfectly positioned to shuttle between these two cultures, bridging the voice and the pen, all the while offering, to the trained imagination, a kind of living inscription.
The thorniness here is the uncertainty about exactly when hand mnemonics flourished. Based on the earliest surviving examples, we could assume the system first appeared around 1,200 years ago. However, it is quite plausible that similar techniques had been in use for even longer. Perhaps no earlier evidence survives because hand mnemonics were so mundane and widely used that no one thought to mention them. Recall that Bede did not illustrate his famed system, and neither did Guido.
It is also difficult to ascertain when and why hand mnemonics faded out and if they have indeed ceased. Many continue to remember the alternation of long and short months by projecting them onto the knuckles, an update of Tabourot’s system. Japanese students, channeling Bede, sometimes use a hand calendar to determine the day of the week on which a given date will fall. In the U.S., hand-based maps—that is, configurations of the hand that resemble a particular geography—are used by residents in places like Michigan, West Virginia, and Alaska. Hand mnemonics are still used to teach the “right-hand rule” in physics classrooms and remain especially popular in medicine, with more introduced all the time. Teams of doctors recently proposed manual systems to remember the expected values for certain diagnostic tests, such as the anatomy of the brachial plexus and the lungs. We increasingly stash our thoughts in virtual realms, but we sometimes still reach for that primordial “digital” repository in our pockets.
