In his day, Julius Caesar was also renowned as a great orator, though neither his rhetoric nor his poems survive. Part of Caesar’s success in defeating his rivals—military and political—was due to his oral powers of persuasion, his ability to paint incandescent pictures of the future greatness of Rome that inspired his fellow countrymen and senators and roused his troops with brilliant images of battlefield glory and the tangible rewards of victory. Thus by the first century B.C., the kinds of things that cultured people wanted to know and why had undergone a fundamental transformation, a transformation that we credit largely to the Greeks and that generations of Roman citizens and subjects adopted, adapted, and spread from Tunis to the Thames and beyond.
In the span of three thousand years, the inscription technologies pioneered by Sumerian scribes had evolved from pressing wedge-shaped styli into clay as tokens of business transactions to full-blown alphabetic writing on sheets of papyrus that look, for all intents and purposes, like the pages of a medieval manuscript. Three thousand years is a long time in human scale, roughly sixty-five or seventy generations if we generously estimate the life span of those reaching adulthood to be forty-five years. The increased urbanization, intensification of agricultural practices, and monumental building projects that produced Egyptian pyramids and the Acropolis of Athens testify how far humans left biological evolution behind them as the primary agent of change. If the Sumerian scribes could look down from some imaginary perch of space-time to behold their first century B.C. brethren, they would see two things quite beyond their imagination.
First was the remarkable new technology of writing that used inks to mark letters on sheets made from papyrus, a plant abundant in the marshlands of the delta of the lower Nile River but unknown in the drier climates of Mesopotamia. The sheets were made of papyrus stalks, pounded together into a fiber that was flexible, relatively strong, paper light, took inks well, was stable in dry climates, and could be rolled up into a tidy little scroll that was easier to handle and store than a clay tablet. They would also have been surprised that the symbols used to convey meaning had changed so dramatically over time, reduced essentially to letters made of a few strokes representing a sound and the letters together comprising an alphabet. The codes for writing had become more economical and made recombination more flexible.
On the other hand, they may have been dismayed to realize that the astounding efficiencies of ink-on-paper writing were bought at the price of durability. The clay tablets the Sumerians wrote on were subject to torching during wartime, just as scrolls burnt in the inferno that consumed the library of Alexandria. But fire does not destroy clay tablets. On the contrary, it preserves them. When exposed to heat in a process known to potters as firing, they became far more durable. An indication of just how stubbornly sturdy clay tablets are is that between five hundred thousand and two million clay tablets have been dug up over the past few centuries, many of them perfectly preserved. They may not be as lightweight and portable as scrolls, let alone books, CD-ROMs, or the silicon chips in our smartphones. But in terms of sheer durability, the technology for writing reached a peak five thousand years ago and has been going downhill ever since.
Our Sumerian scribes gazing down with curiosity at the Mediterranean world of the first century B.C. would also have been surprised by the sheer number of large collections and people who could read them. The literate were a bigger portion of the free population in Greece and Rome than they were likely to have been in Sumerian or Akkadian times. As experts on ancient slavery have pointed out, the freedom from labor enjoyed by the elites of Greece and Rome was bought and paid for by an increased dependence on enslaved labor. It is hard to avoid the conclusion that knowledge grew at the expense of human freedom, especially when we are used to thinking of the former being a precondition for the latter. But the equation was flipped only during the Enlightenment.
Libraries proliferated throughout the ancient world. Besides the collections in Alexandria, there were large libraries in Rhodes, Pergamum, Athens, and Rome, with many smaller collections in other population centers and private libraries in the homes of the cultured rich. But something else, perhaps less visible to the eye but ultimately of greater consequence, had shifted. By the fifth century B.C., the Greeks had embarked on a novel enterprise, the concerted cultivation of knowledge for its own sake. In doing so, they made three contributions to the expansion of human memory whose effects are still playing out today. The first is the creation of mnemonic or memory techniques that tap into a profound understanding of how memory relies on emotion and spatialization, thereby predating contemporary neuroscience’s findings by twenty-five hundred years. The second is the creation of libraries as centers of learning and scholarship, not primarily storage depots for administrative records. And third is recognition of the moral hazards of outsourcing the memory of a living, breathing, thinking, and feeling person to any object whatsoever. By cultivating knowledge for its own sake, they raised the pursuit of beauty and harmony to a level as high as, or higher, than the pursuit of know-how to solve pragmatic problems. Knowledge was not cultivated solely for its instrumental value—its ability to effect change in the world. It acquired an aesthetic dimension, serving to give pleasure and meaning to individuals. And the Greeks insisted linking what we know with what we take responsibility for knowing as a moral matter, a question that has grown acute today, when scientific knowledge is used to create nuclear and biological weapons that can be dropped from robotic planes on civilians and military alike, and to extract energy and food for a ballooning human population that imperils the global environment.
MEMORY PALACES AND MNEMONICS
Cultures that do not develop writing have many ways other than the written word to enhance natural memory. Techniques to store vital information—about plants and animals, weather patterns and seasons, family and foe—are a central feature of all known cultures. They carry knowledge not only in songs, dance, and stories, but also in arrangements of rocks and patterns woven into a fabric. The Mano tribesmen of Liberia select stones to hold their memories. Incans knotted strings of llama silk into specific patterns governed by conventions of meaning, known as quipu, to convey information. These techniques require compressing sometimes lengthy pieces of information into a code. The contents of a message thus encoded could be shared with anyone with knowledge of the code, be it the single individual who created the memory stone or the group of Incans who communicated across their vast Andean empire in the language of knots.
The Greeks are credited with inventing a memory system, or mnemonic (so named after the Greek goddess of memory, Mnemosyne), that is still in use today. Along the way, they made two fundamental discoveries about how the brain forms memories through emotion and spatial thinking. Prizing the art of rhetoric as a civic virtue—democratic citizenship in action, as it were—the Greeks had to perform feats of memorization and recitation. So they built virtual libraries in their minds to store large components of complex knowledge for ease of recall in performance. These virtual libraries came to be known as memory palaces. Each orator was responsible for building his own personal mental memory palace and stocking it with information of his choosing—rhetoric to be delivered at a banquet or an ode to commemorate a victory. (The public sphere was for men only.) Once constructed, the memory palace enabled its architect to retrieve memories as easily as imagining a stroll through this imaginary edifice.
The legendary systematizer of memories and father of mnemonics was the lyric poet Simonides of Ceos (ca. 556–468 B.C.). He was not a man with an unusually good memory, but a man who discovered an unusually good technique for remembering things. Simonides was dining one day with a number of eminent folks when, midbanquet, he was called outside to meet two men. When he went out, he found no one. As he turned back, he saw the building he had just left collapse, crushing everybody inside. The bodies retrieved from the rubble were battered beyond recognition. Yet when called upon to identify the bodies, Simonides was able to rec
all who sat where as they dined. He identified people by the location of their seats around the table.
The first thing to notice is that his memory was formed under extreme duress, the trauma of having escaped a certain death. Emotion in memory formation and retention is primary. It lends brightness to the details of an event and cues the mind to the value of the memory’s content. Emotion is embedded in the content of the event and is part and parcel of what is recalled when a memory is triggered. This affective or emotional nature of memory is responsible for the vividness of painful memories (a crippling vividness in the case of post-traumatic stress disorder). But it is equally the source of great pleasure when, catching the strains of an old song, you remember a certain blissful summer day at the beach when the radio played that tune over and over; or when the smell of caramelized apples takes you back to your grandmother’s kitchen, warm, cozy, and pleasantly humid while outside darkness gathers at the windows and the winds rustle the last leaves on the big red maple by the garden path.
The second thing to notice is that Simonides recalled by visualizing a spatial arrangement. He summoned an image of where people sat around the banquet table in order to call their names to mind. This story, factual or not, makes absolute sense as neuroscience. Long before scientists studied the anatomy of memory, Greeks had figured out how emotion conveys the value of a memory and spatialization determines recall. Both declarative memory—facts, figures, names, dates, events—and spatial navigation are initially processed by the brain’s hippocampus, a small neural structure in the brain. This is the part of the brain Alzheimer’s disease attacks first, producing both memory loss and spatial disorientation among the afflicted. (In 2014, the Nobel Prize in Physiology or Medicine was awarded to three scientists who discovered how some aspects of this information mapping occur.) Without the careful placement of a perception into a spatial grid in the brain, the mind gets lost in the maze of memories crammed into our skulls. And without emotional encoding of value and vividness, that event and every scrap of information associated with it disappears into the anonymous oceans of daily data.
From this discovery of a striking visualization inflected by emotion, Simonides developed his technique. Generations of Greeks, Romans, and Europeans who revived this technique in the Renaissance used his system, based on the imaginary disposition of objects, standing in for ideas, carefully arrayed in an arbitrary space they imagined moving through to reach those ideas. Cicero, a devotee of the technique, wrote:
[Simonides] inferred that persons desiring to train this faculty [of memory] must select places and form mental images of the things they wish to remember and store those images in the places, so that the order of the places will preserve the order of the things, and the image of the things will denote the things themselves, and we shall employ the places and images respectively as a wax writing-tablet and the letters written on it.
Objects were charged with symbolizing the content of a memory, and places were designated as navigation points along routes of retrieval. You could design a building full of long corridors punctuated by doors leading into rooms stocked with specific memories in the guise of designated objects. A raven could stand in for a vision you had in a dream. An armchair might recall the contents of a book you read. The large cannon in the middle of the room might summon up a visit you made to Gettysburg one summer and this puts you in mind of the garden in Delaware you saw on the same trip, the garden you were strolling in when you first heard the story about how your parents met.
Objects alone cannot do the trick. Instead, we use a compression algorithm native to symbolic thought, the use of the concrete as a part to stand in for the whole. In poetics, this part-for-the-whole substitution is termed “synecdoche,” and it proliferates in our language because it is so vivid and efficient. We call the executive branch of the government the White House and the legislative branch Capitol Hill, for example, and government business passing between them is said to go down Pennsylvania Avenue, the name of the boulevard that runs between them. The art of memory simply leverages this mental shortcut.
Recall depends on connections among memories dispersed across far-flung networks of stored information. When we search for a specific memory, we are like fishermen casting nets overboard into the fathomless seas. What we haul up is not any one name or place or event, but a vast web of assorted yet tightly associated facts and figures, contents from the depths of our past jumbled up with the flotsam and jetsam of yesterday’s news. We do not notice all this detritus because we are looking for one thing and ignoring the rest. Recall aided by spatial memory is common, for example, when we try to remember personal names. When we encounter a familiar-looking woman but cannot remember her name, we grope for where we last saw her to recall her name. In a split-second search and retrieval, our mind may fill up with all kinds of associations, but we are not conscious of that because we are focused on spotting just that one name.
For mnemonics to work best, the location in which we place memories should be arbitrary, neither logical nor natural. It could be a landscape—a forest, a garden, a mountain path—anything with strong features easily remarked and remembered. But most people practicing the art of memory choose to construct imaginary buildings. This gives them more control than having to adapt their mental landscapes to the real world. During the Renaissance, when people were expected to be eloquent without resort to teleprompters and even cheap notepaper was nonexistent, hands were used as sites for memorization. The palm was the handiest possible portable mnemonic device. For reasons we do not fully understand, memory can be reinforced and amplified by using physical objects, whether it is a memory stone, a series of knots tied on fingers or into elaborate quipu, or merely an extension of the body itself.
The power of spatial context to aid memory retrieval is the principle behind many residential-care regimes for Alzheimer’s patients. The staff essentially re-create the context of a person’s life by re-creating a room in which they lived. Familiar surroundings cue the patients that they are somewhere safe. The effect is to orient them, calming them by obviating the need to learn an unfamiliar landscape.
The routine of walking through a real space also works to stimulate recollection. Locomotion gets more than just the body moving. It is common for mathematicians, composers, writers, scientists, and anyone else engaged in mental exertion to take a walk when they are stuck, as if moving can literally jog free something that will not budge in their brain. Beethoven, Dickens, and Kierkegaard were all devotees of the long afternoon stroll. We do not know why, let alone how, moderate physical movement stirs up the archives of the mind along with the circulation of the blood. We do know that when researchers long used to browsing library shelves to find something (even if they do not know what it is) complain about missing physical browsing in the online environment, they are doing more than lamenting the loss of a search technique they feel comfortable with. We may refer to the Internet as cyberspace, but its lack of material substance has distinct disadvantages when it comes to finding our way in its dense forests of data. We understand so very little about how real physical space affects memory and vice versa. We know Alzheimer’s patients lose their ability to navigate space and even orient themselves physically in the present, for example, unable to tell where they are because they cannot remember where they came from. And we know the hippocampus maps location cell by individual cell. But how that map is processed into memory remains obscure.
Fortunately, maybe even predictably, we have rediscovered the importance of geography and the art of mapping in the digital age. Virtual representation of space is necessary in the absence of real space because the brain spatializes what it perceives. It is not accidental that many Internet search engines use some form of map to display results. Digital search techniques are good at identity matching, whether we are searching databases for genetic or fingerprint matches, or looking for hypertext links that work through verbal matching and association. But the sense of meaning only arises
from the context of what we perceive. Interactive timelines, maps, charts, and infographics are common now in presentations and online newspapers. They allow people to grasp the import of information quickly by arranging data schematically in a variety of contexts to reveal relationships. Context is spatial. Simonides knew that.
LIBRARIES AS TEMPLES OF LEARNING
The volume of information crossing someone’s horizon is always limited by what is physically accessible. Until roughly 2000 A.D., if someone wanted access to information, they had to go to where the books and journals, maps and manuscripts were—the library. What the Greeks started and the Romans elaborated was the transformation of a library from a depot of administrative records to a workshop for knowledge creation.
The library at Alexandria was built on a strip of land where the Nile delta meets the Mediterranean. The city served as the gateway to the interior of the country and Egypt’s portal to the world. What we call the library was a collection of manuscripts housed in a separate building within a temple complex dedicated to the muses. The library’s birth and death are shrouded in legends, but we think the library was created sometime in the fourth or third century B.C. and died a slow death from repeated armed assaults, collateral damage of war, followed by studied neglect over the course of many centuries as it was dispersed or destroyed and eventually disappeared. The library has no death date. It did not really die. It faded away.
In its heyday, it served as a gathering point for copying documents from around the Mediterranean. Egyptian rulers would “borrow” manuscripts from vessels that came into port and copy them for the collections. (They often kept the originals and returned copies to their owners.) At its peak in the early centuries of the Roman Empire, the collection may have been as large as seven hundred thousand scrolls comprising tens of thousands of individual works, though an unknown number of those were likely to be variants or duplicates.
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