|Giulio Camillo, L'idea del Theatro, 1550.|
In summarizing this memory system, he explained that these palaces, pavilions, divans were mental structures to be kept in one's head, not solid objects to be literally constructed out of "real" materials. Ricci suggested that there were three main options for such memory locations. First, they could be drawn from reality - that is, from buildings that one had been in or from objects that one had seen with one's own eyes and recalled in one's memory. Second, they could be totally fictive, products of the imagination conjured up in any shape or size. Or third, they could be half real and half fictive, as in the case of a building one knew well and through the back wall of which one broke an imaginary door as a shortcut to new spaces, or in the middle of which one created a mental staircase that would lead one up to higher floors that had not existed before.
The real purpose of all these mental constructs was to provide storage spaces for the myriad concepts that make up the sum of our human knowledge. To everything that we wish to remember, wrote Ricci, we should give an image; and to every one of these images we should assign a position where it can repose peacefully until we are ready to reclaim it by an act of memory. Since this entire memory system can work only if the images stay in the assigned position and if we can instantly remember where we stored them, obviously it would seem easiest to rely on real locations which we know so well that we can never forget them. But that would be a mistake, thought Ricci. For it is by expanding the number of locations and the corresponding number of images that can be stored in them that we increase and strengthen our memory. Therefore the Chinese should struggle with the difficult task of creating fictive places, or mixing the fictive with the real, fixing them permanently in their minds by constant practice and review so that at last the fictive spaces become "as if real, and can never be erased".
Jonathan D. Spence, The Memory Palace of Matteo Ricci, Penguin Books, 1984, p.1-2.