"One must have a rigid, easily retained order, with a definite beginning. Into this order one places the components of what one wishes to memorize and recall. As a money-changer ("nummularium") separates and classifies his coins by type in his money bag ("sacculum," "marsupium"), so the contents of wisdom's storehouse ("thesaurus," "archa"), which is the memory, must be classified according to a definite, orderly scheme."
O'Keefe and Nadel refer to "'the method of loci', an imaginal technique known to the ancient Greeks and Romans and described by Yates (1966) in her book The art of memory as well as by Luria (1969). In this technique the subject memorizes the layout of some building, or the arrangement of shops on a street, or any geographical entity which is composed of a number of discrete loci. When desiring to remember a set of items the subject literally 'walks' through these loci and commits an item to each one by forming an image between the item and any distinguishing feature of that locus. Retrieval of items is achieved by 'walking' through the loci, allowing the latter to activate the desired items. The efficacy of this technique has been well established (Ross and Lawrence 1968, Crovitz 1969, 1971, Briggs, Hawkins and Crovitz 1970, Lea 1975), as is the minimal interference seen with its use."