The following excerpt is from the Latin text Ad Herennium. Though written many centuries ago, the information it provides on improving the memory is still as useful today as it was when originally written. I suggest reading it before continuing on to the lessons on improving the memory.
Now let me turn to the treasure-house of the ideas supplied by Invention, to the guardian of all the parts of rhetoric, the Memory.
The question whether memory has some artificial quality, or comes entirely from nature, we shall have another, more favourable, opportunity to discuss. At present I shall accept as proved that in this matter art and method are of great importance, and shall treat the subject accordingly. For my part, I am satisfied that there is an art of memory — the grounds of my belief I shall explain elsewhere. For the present I shall disclose what sort of thing memory is.
There are, then, two kinds of memory: one natural, and the other the product of art. The natural memory is that memory which is imbedded in our minds, born simultaneously with thought. The artificial memory is that memory which is strengthened by a kind of training and system of discipline. But just as in everything else the merit of natural excellence often rivals acquired learning, and art, in its turn, reinforces and develops the natural advantages, so does it happen in this instance. The natural memory, if a person is endowed with an exceptional one, is often like this artificial memory, and this artificial memory, in its turn, retains and develops the natural advantages by a method of discipline. Thus the natural memory must be strengthened by discipline so as to become exceptional, and, on the other hand, this memory provided by discipline requires natural ability. It is neither more nor less true in this instance than in the other arts that science strives by the aid of innate ability, and nature by the aid of the rules of art. The training here offered will therefore also be useful to those who by nature have a good memory, as you will yourself soon come to understand. But even if these, relying on their natural talent, did not need our help, we should still be justified in wishing to aid the less well-endowed. Now I shall discuss the artificial memory.
The artificial memory includes backgrounds and images. By backgrounds I mean such scenes as are naturally or artificially set off on a small scale, complete and conspicuous, so that we can grasp and embrace them easily by the natural memory — for example, a house, an intercolumnar space, a recess, an arch, or the like. An image is, as it were, a figure, mark, or portrait of the object we wish to remember; for example, if we wish to recall a horse, a lion, or an eagle, we must place its image in a definite background. Now I shall show what kind of backgrounds we should invent and how we should discover the images and set them therein.
Those who know the letters of the alphabet can thereby write out what is dictated to them and read aloud what they have written. Likewise, those who have learned mnemonics can set in backgrounds what they have heard, and from these backgrounds deliver it by memory. For the backgrounds are very much like wax tablet or papyrus, the images like letters, the arrangement and disposition of the images like the script, and the delivery is like the reading. We should therefore, if we desire to memorize a large number of items, equip ourselves with a large number of backgrounds, so that in these we may set a large number of images. I likewise think it obligatory to have these backgrounds in a series, so that we never by confusion in their order be prevented from following the images — proceeding from any background we wish, whatsoever its place in the series, and whether we go forwards or backwards — nor from delivering orally what has been committed to the backgrounds.
For example, if we should see a great number of our acquaintances standing in a certain order, it would not make any difference to us whether we should tell their names beginning with the person standing at the head of the line or at the foot or in the middle. So with respect to the backgrounds. If these have been arranged in order, the result will be that, reminded by the images, we can repeat orally what we committed to the backgrounds, proceeding in either direction from any background we please. That is why it also seems best to arrange the backgrounds in a series.
We shall need to study with special care the backgrounds we have adopted so that they may cling lastingly in our memory, for the images, like letters, are effaced when we make no use of them, but the backgrounds, like wax tablets, should abide. And that we may by no chance err in the number of backgrounds, each fifth background should be marked. For example, if in the fifth we should set a golden hand, and in the tenth some acquaintance whose first name is Decimus, it will then be easy to station like marks in each successive fifth background.
Again, it will be more advantageous to obtain backgrounds in a deserted than in a populous region, because the crowding and passing to and fro of people confuse and weaken the impress of the images, while solitude keeps their outlines sharp. Further, backgrounds differing in form and nature must be secured, so that, thus distinguished, they may be clearly visible; for if a person has adopted many intercolumnar spaces, their resemblance to one another will so confuse him that he will no longer know what he has set in each background. And these backgrounds ought to be of moderate size and medium extent, for when excessively large they render the images vague, and when too small often seem incapable of receiving an arrangement of images. Then the backgrounds ought to be neither too bright nor too dim, so that the shadows may not obscure the images nor the lustre make them glitter. I believe that the intervals between backgrounds should be of moderate extent, approximately thirty feet; for, like the external eye, so the inner eye of thought is less powerful when you have moved the object of sight too near or too far away.
Although it is easy for a person with a relatively large experience to equip himself with as many and as suitable backgrounds as he may desire, even a person who believes that he finds no store of backgrounds that are good enough, may succeeded in fashioning as many such as he wishes. For the imagination can embrace any region whatsoever and it at will fashion and construct the setting of some background. Hence, if we are not content with our ready-made supply of backgrounds, we may in our imagination create a region for ourselves and obtain a most serviceable distribution of appropriate backgrounds. On the subject of backgrounds enough has been said; let me now turn to the theory of images.
Since, then, images must resemble objects, we ought ourselves to choose from all objects likenesses for our use. Hence likenesses are bound to be of two kinds, one of subject-matter the other of words. Likenesses of matter are formed when we enlist images that present a general view of the matter with which we are dealing; likenesses of words are established when the record of each single noun or appellative is kept by an image. Often we encompass the record of an entire matter by one notation, a single image.
For example, the prosecutor has said that the defendant killed a man by poison, has charged that the motive for the crime was an inheritance, and declared that there are many witnesses and accessories to this act. If in order to facilitate our defence we wish to remember this first point, we shall in our first background form an image of the whole matter. We shall picture the man in question as lying ill in bed, if we know his person. If we do not know him, we shall yet take some one to be our invalid, but a man of the lowest class, so that he may come to mind at once. And we shall place the defendant at the bedside, holding in his right hand a cup, and in his left tablets, and on the fourth finger ram’s testicles. In this way we can record the man who was poisoned, the inheritance, and the witnesses. In like fashion we shall set the other counts of the charge in backgrounds successively, following their order, and whenever we wish to remember a point, by properly arranging the patterns of the backgrounds and carefully imprinting the images, we shall easily succeed in calling back to mind what we wish.
When we wish to represent by images the likenesses of words, we shall be undertaking a greater task and exercising our ingenuity the more. This we ought to effect in the following way: Iam domum itionem reges Atridae arant. “And now their home-coming the kings, the sons of Atreus, are making ready.”
If we wish to remember this verse, in our first background we should put Domitius, raising hands to heaven while he is lashed by the Marcii Reges — that will represent “Iam domum itionem reges” (“And now their home-coming the kings,”); in the second background, Aesopus and Cimber being dressed as for the rôles of Agamemnon and Menelaüs in Iphigenia — that will represent “Atridae parant” (“the sons of Atreus, making ready”). By this method all the words will be represented. But such an arrangement of images succeeds only if we use our notation to stimulate the natural memory, so that we first go over a given verse twice or three times to ourselves and then represent the words by means of images. In this way art will supplement nature. For neither by itself will be strong enough, though we must note that theory and technique are much the more reliable. I should not hesitate to demonstrate this in detail, did I not fear that, once having departed from my plan, I should not so well preserve the clear conciseness of my instruction.
Now, since in normal cases some images are strong and sharp and suitable for awakening recollection, and others so weak and feeble as hardly to succeed in stimulating memory, we must therefore consider the cause of these differences, so that, by knowing the cause, we may know which images to avoid and which to seek.
Now nature herself teaches us what we should do. When we see in everyday life things that are petty, ordinary, and banal, we generally fail to remember them, because the mind is not being stirred by anything novel or marvellous. But if we see or hear something exceptionally base, dishonourable, extraordinary, great, unbelievable, or laughable, that we are likely to remember a long time. Accordingly, things immediate to our eye or ear we commonly forget; incidents of our childhood we often remember best. Nor could this be so for any other reason than that ordinary things easily slip from the memory while the striking and novel stay longer in mind. A sunrise, the sun’s course, a sunset, are marvellous to no one because they occur daily. But solar eclipses are a source of wonder because they occur seldom, and indeed are more marvellous than lunar eclipses, because these are more frequent. Thus nature shows that she is not aroused by the common, ordinary event, but is moved by a new or striking occurrence. Let art, then, imitate nature, find what she desires, and follow as she directs. For in invention nature is never last, education never first; rather the beginnings of things arise from natural talent, and the ends are reached by discipline.
We ought, then, to set up images of a kind that can adhere longest in the memory. And we shall do so if we establish likenesses as striking as possible; if we set up images that are not many or vague, but doing something; if we assign to them exceptional beauty or singular ugliness; if we dress some of them with crowns or purple cloaks, for example, so that the likeness may be more distinct to us; or if we somehow disfigure them, as by introducing one stained with blood or soiled with mud or smeared with red paint, so that its form is more striking, or by assigning certain comic effects to our images, for that, too, will ensure our remembering them more readily. The things we easily remember when they are real we likewise remember without difficulty when they are figments, if they have been carefully delineated. But this will be essential — again and again to run over rapidly in the mind all the original backgrounds in order to refresh the images.
I know that most of the Greeks who have written on the memory have taken the course of listing images that correspond to a great many words, so that persons who wished to learn these images by heart would have them ready without expending effort on a search for them. I disapprove of their method on several grounds. First, among the innumerable multitude of words it is ridiculous to collect images for a thousand. How meagre is the value these can have, when out of the infinite store of words we shall need to remember now one, and now another? Secondly, why do we wish to rob anybody of his initiative, so that, to save him from making any search himself, we deliver to him everything searched out and ready? Then again, one person is more struck by one likeness, and another more by another. Often in fact when we declare that some one form resembles another, we fail to receive universal assent, because things seem different to different persons. The same is true with respect to images: one that is well-defined to us appears relatively inconspicuous to others. Everybody, therefore, should in equipping himself with images suit his own convenience. Finally, it is the instructor’s duty to teach the proper method of search in each case, and, for the sake of greater clarity, to add in illustration some one or two examples of its kind, but not all. For instance, when I discuss the search for Introductions, I give a method of search and do not draught a thousand kinds of Introductions. The same procedure I believes be followed with respect to images.
Now, lest you should perchance regard the memorizing of words either as too difficult or as of too little use, and so rest content with the memorizing of matter, as being easier and more useful, I must advise you why I do not disapprove of memorizing words. I believe that they who wish to do easy things without trouble and toil must previously have been trained in more difficult things. Nor have I included memorization of words to enable us to get verse by rote, but rather as an exercise whereby to strengthen that other kind of memory, the memory of matter, which is of practical use. Thus we may without effort pass from this difficult training to ease in that other memory. In every discipline artistic theory is of little avail without unremitting exercise, but especially in mnemonics theory is almost valueless unless made good by industry, devotion, toil, and care. You can make sure that you have as many backgrounds as possible and that these conform as much as possible to the rules; in placing the images you should exercise every day. While an engrossing preoccupation may often distract us from our other pursuits, from this activity nothing whatever can divert us. Indeed there is never a moment when we do not wish to commit something to memory, and we wish it most of all when our attention is held by business of special importance. So, since a ready memory is a useful thing, you see clearly with what great pains we must strive to acquire so useful a faculty. Once you know its uses you will be able to appreciate this advice. To exhort you further in the matter of memory is not my intention, for I should appear either to have lacked confidence in your zeal or to have discussed the subject less fully than it demands. – English Translation by Harry Caplan (Loeb, 1954)