Mnemonics (Gr.Mnemonics 1100333 memory), the art of rendering artificial aid to the memory by associating in the mind things difficult to remember with those which are easy of recollection, so that the former may be retained and brought to mind by association with the latter. The art is supposed by some writers to have originated with the Egyptians, but the first person who reduced it to a system was, according to Cicero, the poet Simonides of Cos (about 500 B. C). Having been called from a banquet just before the roof of the house fell and crushed all the rest of the company, he found on returning that the bodies were so mutilated that no individual could be recognized; but by remembering the places which they had severally occupied at table he was able to distinguish them. He was thus led to remark that the order of places may by association suggest the order of things. The principles of the art were introduced at Rome and developed by Metrodorus, and Cicero and Quintilian both advocated the plan of associating thoughts and words with particular places, images, or signs which might be recalled at pleasure.

One of the earliest modern works on the subject is the Fornix (1491) of Petrus Ravennas, professor of canon law in Padua. One of his artifices was to make beautiful maidens the letters of an alphabet. John Romberch de Krypse, in his Congestorium Artificiosm Memories (1533), recommended the division of the walls of a series of rooms into separate spaces, each of which was to be marked with numerical, literal, and symbolical alphabets. The distinct rooms were to be devoted, like the alcoves of a library, to distinct classes of subjects; and the nomenclature having once been mastered, the suggestions of local relation would enable a man to repeat hundreds of words or ideas that had no real connection with one another. The same method is developed further in the " Castel of Memorie " of Guilielmo Grataroli of Bergamo, published in English in 1562. The Are Memories of Marafortius (1602) grouped all necessary reminiscences around 44 images contained in the palms of the hands. Giambattista della Porta, in his Ars Heminiscendi (1602), seems to have first employed the mode of writing now common in rebuses. About 1609 Lambert Schenkel astonished all classes in France, Germany, and the Netherlands by his mnemonic performances.

His system, which was similar to that of Simonides, was obscurely explained in his Gazophylacium Artis Memoriae (1610). He was succeeded at the university of Paris, where he taught for many years, by his pupil Martin Sommer, who became equally celebrated. More elaborate than any preceding scheme was the repository for ideas suggested by John Wallis in his Mnemoniaca (1618). This repository was to be a series of imaginary theatre-shaped edifices with their interior walls variously divided and colored. Every person was to have his -repository constantly present before his mind, within which all his ideas were to be arranged according to their qualities, quantities, positions, and colors. The plan only became more complicated as improved by Henry Herdson (1651). The Memoria Technica of Richard Grey (1730; new ed., 1851) contains a system which many have found useful in remembering dates and numbers. Letters are substituted for figures and combined into words; certain consonants are selected for this purpose, the vowels serving only to connect them.

Grey's letters, which were adopted without reference to any similarity to the figures they stand for, are as follows:

1 1»

2 d.

8 t.

4 f.

5

1

6 s.

7 P.

8 k.

9 n o z.

Words formed from those letters by combination with any of the vowels are more easily numbered than the figures they represent. The most complicated system of mnemonics is that of Fainaigle, who began to lecture in Paris in 1807 and in England in 1811. He divides the walls, ceiling, and floor of a room into 50 imaginary equal compartments. To each compartment is assigned a particular hieroglyphic, with which it is indelibly associated. These elements having been thoroughly mastered, some association, no matter how ridiculou-. is formed between the object to be remembered and one of the hieroglyphs. The substitution of letters for figures also belongs to his system. His table is as follows: l t.

2 n.

8 m.

4 r.

5

1

6 d.

7 ckgq.

8 bvw.

9 Pf.

0 sxz.

He selected these letters on account of some similarity to or association with the figure represented; as, for example, t resembles the figure 1. n with two strokes suggests 2, m with three strokes suggests 3, r occurs in the word denoting four in the European languages, etc. Fainaigle published a work in English illus-trative of his system, entitled "The New Art of Memory" (London, 1812). His system was improved by Aimee Paris (Principes et applications direrses de hi mnemotechnie, 7th ed., Paris, 1833), who applied his method to chronology, geography, jurisprudence, mathematical formula, and the nomenclature of all the sciences. Further modifications were made by F. Fauvel-Gouraud, who taught in the United States and published " Phreno-Mnemotechnic Dictionary' (part i., New York, 1844), and "Phreno-Mnemotechny, or the Art of Memory " (1845). Among other late writers on mnemonics are Gen. Bern, Expose general de la methode mnemonipie polonaise, etc. (Paris and Leipsic, 1839), an enlargement of Jazwinski's system; Hermann Kothe, System der Mnemo-nik (Gassel, 1853); and Karl Otto-Reventlow, Mnnnoterhnisrher Commentar zur allgemeinen Weltgwhirhte (Stuttgart, 1861).