History of Memory: Ad Herennium by Cicero – Mnemonic Devices


Did you know that all memory devices, or mnemonics, trace their history back to one book? The Ad Herennium is the foundational book on the Art of Memory.

Apart from any other writing in the history of mnemonics and a trained memory, the Ad Herennium is a foundational work upon which all other written treatises on memory are built upon. Thought to have been written by Cicero or Tullius by tradition, this claim is now disputed , the Ad Hernnium was written circa 86-82 B.C.as a book on rhetoric.

Memory – The Custodian of Rhetoric

The author dedicates a section of his book on rhetoric to memory. The author of Ad Herennium declares, “…Now let us turn to the treasure-house of inventions, the custodians of all the parts of rhetoric, memory.” He continues on to state that there are two kinds of memory, one natural, the other artificial…“The artificial memory is that memory which is strengthened by a kind of training and system of discipline.”

This book is thought to draw upon earlier Greek resources on memory training, all of which are lost – it is the only Latin treatise available from the time period available on the artificial memory. The Ad Herennium can be difficult to understand as it seems to draw upon earlier works that take for granted certain memory principles unknown to us today.

Regardless, it is upon this work that all later medieval treatises on memory would be based upon, “…the astonishing developments of the art of memory in the sixteenth century…still preserve the ‘Ad Herennium’ outlines below all their complex accretions.”

Two Kinds of Memory

At the start the author differentiates between two kinds of memory, one the inborn natural memory, “and the other the product of art…The artificial memory is that memory which is strengthened by a kind of training and system of discipline.”


He then proceeds to discuss the importance of “backgrounds”, that is, locations or loci. These places are to be arranged in a logical, sequential order that does not deviate. These backgrounds or places are to be a type of ‘placeholder’ for images to be stored upon. The images are those things which are to be remembered – either things (memoria rerum) or words (memoria verbum).

By establishing a fixed pattern of backgrounds or locations, new images may be placed without damaging the locations, “…for the images, like letters, are effaced when we make no use of them, but the backgrounds, like wax tablets should abide.” These locations may be real locations, such a moving through a church and fixing locations in the memory, or entirely fictitious.

Memoria Rurum and Memoria Verbum

The author then discusses the two types of images necessary to be placed upon the loci, memory for things and for words. Both enlist the usage of images that will ‘cue’ the desired memory.

The author states that memoria verbum is more difficult than memoria rerum, stating, “…we shall be undertaking a greater task and exercising our ingenuity the more.” The author advocates going over verses that are to be committed to memory, “…twice or three times to ourselves and then represent the words by means of images.” By combining repetition with images the natural memory is helped and “stimulated” by the use of such means when exercising memoria verbum, “In this way art will supplement nature.”

Striking Images

The next section of Ad Hernnium discussses what type of images will best be remembered. He argues, from nature, that the unusual, disfigured or striking images are most easily remembered without effort:

Now nature herself teaches us what we should do. When we see in everyday life things that are pretty, ordinary, and banal, we generally fail to remember them…But if we see or hear something exceptionally base, dishonorable, extraordinary, great, unbelievable, or laughable, that we are likely to remember a long time…Nor could this be so for any other reason that ordinary things easily slip from the memory while the striking and novel stay longer in mind.

Teaching the Art of Memory

The author of Ad Herennium then moves to giving advice to the instructor of the art of memory. He states that the instructor should not give all the images to the students, but rather give a few examples, and make the students conjure up their own images, suitable to what they would like to remember. For to one student one image may be striking, yet to another it leaves a vague impression, “…one person is more struck by one likeness, and another more by another…one that is well defined to us appears relatively inconspicuous to others.”

Mnemonics Require Devotion and Toil

The author closes this section with an admonition to hard work and effort to obtain a good 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.” The author then declares the value of memory as a practical tool in everyday life, “Indeed there is never a moment when we do not wish to commit something to memory…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.”