The main dinner course was just being served in the massive, ancient Greek hall when the expansive ceiling collapsed, crushing every one of the many guests in their seats. Not a single attendee survived, except for the poet Simonides, who had left the room just before the tragedy. In the days that followed, workers who lifted the heavy rubble found that the victims were so horribly disfigured that they were impossible to identify. But Simonides was able to help. By mentally walking alongside the long table, he found he could reconstruct which guest had been sitting in which place. Based on where the bodies lay, he named each one of the deceased.

Four hundred years later Roman rhetorician Cicero (10643 B.C.) related Simonides story in one of his instructional books on learning and memory. Whether the diners' deaths actually happened is not clear, but according to legend, Cicero wrote, the ceiling collapse motivated Simonides to develop a visual memory technique that still prevailed in Cicero's day, used widely by the Roman Empire's politicians and lawyers. These professionals were looked down on if they could not memorize the long speeches they often had to give; it was important for them to recite complex strains of an argument in moving oration.

The memory trick, or mnemonic, that Simonides had discovered was indeed a powerful device. Cicero made the lesson plain in his book: memory is well served when a list of names, objects or ideas is visually arranged in a three-dimensional environment.

Many people who exhibit extraordinary memory capabilities use this technique, including winners of world memory championships [see box on opposite page]. Although the method may seem peculiar at first, any person can use it to improve their recollection of anything, from shopping lists to lecture outlines. Once you find a way to "see" the items you must remember, you can use the trick on different strings of information. Most current self-help books on improving memory or mental acuity also endorse this method, using, of course, modern strategies--and environments--that build on this ancient approach.

Soap Cushions
The mnemonic device, known as the loci method, involves placing mental pictures of items in specific locations inside a room, in a specific order. A person can then "walk" through the room and see all the objects that must be recalled. Each person must develop his or her own locational system. Teachers in antiquity recommended using public places such as temples or meeting houses as sites for spatial memory training; an individual would stand inside a temple and memorize the position of each column and statue, from the main entrance, along the right wall, across the front, back down the left wall, and so on. Each item from a list would then be assigned to a column, statue or other feature, in a given order. Later, the memorizer would visualize the room to find each item.

Today your apartment or house is often the best choice for such an exercise. To begin, define a specific route through each room and order the objects you come across: first there is the foyer, inside which is a small table, mirror, hook for keys, rug and closet door. Next is the living room, with a sofa, radiator, television and ceiling light. It is important to always follow the same sequence--to imprint a fixed locational system in your mind, which can represent standard items such as individual cards in a deck or be augmented to allow for new contents whenever a new list is needed.

As an example, let us say you are going grocery shopping and have nine items to remember: eggs, cheese, spaghetti, fish, bread, soap, butter, salami and cereal. Imagine three rooms in your home, each containing three items from the list. You enter the foyer and hang your keys on the hook shaped like a loaf of bread. You walk across the rug, but it is made of salami slices, and look into a mirror that has two fried eggs stuck to it. In the living room, the TV has become an aquarium in which a big fish swims. The fish is looking across the room at the radiator, on which a stick of butter sits, melting. The melting butter drips down onto the sofa, whose cushions are made of bars of soap [see illustration on opposite page]. In the den you see a computer mouse nibbling at some cheese. The bookshelf above it supports a thick book--the cereal box--and the curtain rod over the window is holding curtains made of woven spaghetti.

Each station, such as the mirror and sofa, is now connected to a particular item. If the following week's list contains a chocolate bar but no cereal, then the bookshelf would be made of chocolate, but the thick book would be missing. This way, various shopping lists can be remembered, with commonly purchased items such as eggs appearing regularly and occasional items such as a chocolate bar appearing sporadically when needed.

Once you have worked with a set sequence for some time--say, 10 locations in each of three rooms--more rooms can be added, increasing your memory storage capacity. Regular training is required for success, however. "Without constant practice," states an anonymous Roman book of rhetoric, Ad Herennium, "the rules will be practically useless. You must see to it that you have as many locations available to you as possible. The insertion of images must be practiced on a daily basis." Adept students of the discipline can build up an incredible number of locations. In modern-day memory competitions, contestants may memorize more than 1,000 numbers in a sequence or playing cards shuffled randomly in multiple decks. Some individuals can repeat a lengthy poem in its entirety after hearing it only once and can retell it with the stanzas in reverse order.

Your Neighbor, the Tennis Racket
Familiarity with the locational system is key, and it should remain unchanged. That is why practice matters. Compiling items from a list should also be done in creative ways, using images that are striking or whimsical--like a couch with soap cushions. Ad Herennium explains this in simple, logical terms: when we "see or hear something mean, big, unbelievable or ridiculous, we will probably think on it long and hard." Sunrises and sunsets are commonplace, but a solar eclipse is not likely to be forgotten. It is therefore important to choose images that resonate on an emotional level.

This is how the champion mnemonists work [see box above]. They use other tricks we commoners can exploit, too. For example, word memories can be helpful when meeting new people: Alan becomes "gallon," Tony becomes "pony," and Amanda becomes "panda." Or you can use object memory to connect names with things based on their context; you can remember the first names of your new neighbors Alexander and Serena as a telephone (Graham Bell) and tennis racket (Williams).

With practice, you can build your visual maps to great degrees. One predecessor of today's memory champions was Peter of Ravenna, a jurist in the late Middle Ages and author of a Latin handbook on memory strategies. Peter traveled extensively in Italy, and whenever he arrived in a new city he would visit churches and cloisters and memorize their layouts. Over time he built up an impressive collection of remembered spaces--more than 100,000 locations, according to his own claims. Whether or not that number was true, he could recite in public entire law books with commentaries, innumerable Bible passages as well as hundreds of classical quotations. Given those feats, the rest of us should at least be able to handle a trip to the grocery store.