For those interested in the basics of the memory palace technique, you are best off reading the second half of De Umrbis Idearum first. The core of the system is very simple:
Bruno mentions all of these rule, and offers a number of good suggestions:
The simplest use of images is for direct representations, such as the image of an upraised hand to represent the number five, or a smiling face for “happiness”, or Barack Obama to remember the word “President”. A more advanced technique involves using a set of images to represent letters or syllables. Bruno spends a fair amount of the book describing several lists of images. The first contains a list of thirty images largely taken from Ovid’s Metamorphoses, the second a list of inventors or creators of things culled from a variety of sources, and the last a set of astronomical/astrological images. Each figure represents a consonant-vowel combination in Latin, Greek or Hebrew lettering, with the Greek and Hebrew letters pulling extra duty as dipthongs in Latin or Italian.
The listed people may be used alone or in groups, and in the case of the first two lists, each person is listed in conjunction with an action and an object, all representing the same letter combination, and each capable of standing for that letter combination in an image. Each composed image may therefore be used to hold three letters or syllables by recombining the person, action and object depicted (see Joshua Foer’s Moonwalking with Einstein for examples). In the modern era, this is called the PAO system. The modern user with less familiarity with classical education may wish to select figures from literature, history or film.