originated with the author of the Ad Herennium. The technique is also mentioned by Cicero and Quintilian. According to the account in the Ad Herennium (Book III) backgrounds or 'places' are like wax tablets, and the images that are 'placed' on or within them are like writing. Real physical locations were apparently commonly used as the basis of memory places, as the author of the Ad Herennium suggests 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. However, real physical locations were not the only source of places. The author goes on to suggest 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. Places or backgrounds hence require, and reciprocally impose, order (often deriving from the spatial characteristics of the physical location memorized, in cases where an actual physical structure provided the basis for the 'places'). This order itself organizes the images, preventing confusion during recall. The anonymous author also advises that places should be well lit, with orderly intervals, and distinct from one another. He recommends a virtual 'viewing distance' sufficient to allow the viewer to encompass the space and the images it contains with a single glance. Turning to images, the anonymous author asserts that they are of two kinds: those establishing a likeness based upon subject, and those establishing a likeness based upon a word. This was the basis for the subsequent distinction, commonly found in works on the art of memory, between 'memory for words' and 'memory for things'. He provides the following famous example of a likeness based upon subject: 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 defense 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