Rhetorica ad Herennium

The Rhetorica ad Herennium was one of the most popular books on rhetoric during the middle ages and the renaissance. It covers the subject of rhetoric in a very structured form, and its structure for arguments is very familiar to anyone who has written a five part essay. It covers many different important areas in the art of discourse, but the one I will focus on here is its treatment of the Art Of Memory and the memorization of speeches. It is the oldest known description of the Method of Loci comes from this text, written around 200 BC. It is a great classical start for an education in memory, and it is on this aspect of the Ad Herennium that this page focuses. This book is worthwhile for people interested in public speaking and arguments as well, if that is something that is interesting to you, I would suggest reading the whole document.

There is a scanned copy of the Rhetorica ad Herennium available online. All references in this page will use this translation of the Latin text.

The treatment of the Art of Memory starts on page 205 of this translation, Book 3, Section 16. This treatment of memory finishes at the end of Book 3, on page 225. Since this version of the Ad Herennium also contains Latin text, there are only 10 short pages describing our topic. It is a very small investment in time to read and understand this classical treatment of memory, for it can help improve your memory skill for a lifetime. What follows are my notes from a critical reading of the text. I have taken slight liberties with the examples at times to make them more clear to a modern reader. The examples in this book are mostly for a person familiar with the experiences and recent history experienced by a Roman from 200 BC, so they don't always make immediate sense to the modern reader.

Notes on Memory from the Ad Herennium

According to the book there are two kinds of memory. One natural, the other the product of art.

  1. The natural memory is that memory internal to our minds, born simultaneously with thought

  2. Artificial memory is improved by a kind of training and discipline.

Both are important, natural memory often rivals the art. Art in turn reinforces and improves natural memory.

The training offered by the Ad Herennium will be most useful to those who by nature have a good memory.

Artificial Memory

Artificial memory includes backgrounds and images.

  1. Backgrounds- There are scenes in the minds eye. A house, building, a pathway are examples.

  2. Image- These are representations of what we want to remember.

Backgrounds are like paper while images are like the letters or words.

To remember a large number of items, we must have a large number of backgrounds to deposit our images. It is also important to arrange these backgrounds in a series. We should always be able to arrange these items in order by following the natural order of our backgrounds. If we know our backgrounds well, there is nothing stopping us from following our images forward or backward.

We should study our backgrounds with great care so they will be lasting in our memory. A background is a more permanent thing than an image. If we no longer need it we can discard an image from our memory, but the background remains.

It is more helpful to build backgrounds that are deserted. If our background has the continual coming and going of people it can confuse and weaken our images. Furthermore, each background should be different enough from the others so that you don't get confused by the similarity. You then will have difficulty remembering what is placed in each background.

The backgrounds should be of moderate size, medium extent, and not too bright or dim. If the background is too large, bright or dim you risk overpowering the images.

A good rule would be separating each interval in the backgrounds by thirty feet. This gives you enough space between images so that they don't mix in your field of view.

Backgrounds can come from direct experience of a place or can be invented. Imagination is powerful for fashioning backgrounds.


Images must resemble objects.

Images can represent the gist of a subject, or could be likenesses in correspondence to exact words when exactitude is important.

Often we can represent an entire matter by a single image. We should combine multiple aspects together in one single image. Perhaps we are to remember a particular person killed another by poison for an inheritance. We can imagine a sickly man on a mountain of gold coins being offered a foul liquid from a cup held by our perpetrator.

When we want to represent images as likenesses of words, it is a more difficult task. It is important to go over the verse several times, repeating it to ourselves to stimulate our natural memory. Then we can come up with images to represent the words. Either technique alone will not be so good, but used together the phrase is much more memorable.

Quality of Images

Some images are strong and sharp in ones memory. Others are faded or muddled, hard to remember. We must figure out the cause of these differences, so we know which kinds of images to seek.

Ordinary things are not memorable, our mind is not stirred because there is nothing novel or marvelous. But if we see or hear something exceptionally base, dishonorable, extraordinary, great, unbelievable, or laughable, that we are likely to remember for a long time. Accordingly, this we see from day to day we commonly forget; incidents from our childhood we often remember best. This is for no other reason than that ordinary things easily slip from our memory while striking and novel things stay longer in the mind. Nature shows us 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.

We ought, then, to set up images of a kind that will stick longest in the memory. We shall do so if we make the images as striking as possible. If the images are of exceptional beauty or singular ugliness, they will be memorable. Perhaps we might stain them with blood, cover them in mud or red paint. In so doing we make them more striking. If we also assign comic effects to our images we will remember them with less difficulty.

Sets of Images

It is not a good idea to learn this technique by looking at or using someone elses list of images for words or concepts. Everyones mind works differently, what is memorable to one might not be to another. The journey itself of creating the images also helps cement them in our mind. It is the instructor's duty to teach the proper method of searching for images and to give one or two examples but not to give a pre-built set of images ready to use.

Memorizing Words

Maybe you regard memorizing of words either as too difficult or of two little use, and feel content to just memorize the meaning of something. It might seem as being easier or more useful, but I must advise you that I do not disapprove of memorizing words. I believe that those who wish to do easy things without trouble and toil must previously have been trained in more difficult things. I have not included memorization of words to enable us to get verse by rote either. Memorizing words is an exercise whereby to strengthen your memory for content and ideas, 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 it 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 practice 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. We wish it most when we are working on something of special importance. So, since a ready memory is a useful thing, you clearly see with what great pains we must strive to acquire so useful a faculty.