MNEMONICS, the general name applied to devices for aiding the memory. Such devices are also described as memoria technica. The principle is to enable the mind to reproduce a rela tively unfamiliar idea, and specially a series of dissociated ideas, by connecting it, or them, in some artificial whole, the parts of which are mutually suggestive. Among the most famous examples of metrical mnemonics are the "gender rhymes" of the Latin gram mars, the hexameter lines (especially that beginning "Barbara Celarent") invented by logicians (for a list see Baldwin's Dict. of Philos., vol. ii., s.v. "Mnemonic Verses"), the verse for remem bering the number of days in the months ("Thirty days bath September, April, June and November"). Other devices are numerous.
Systems.—Mnemonic devices were much cultivated by Greek sophists and philosophers, and are repeatedly referred to by Plato and Aristotle. In later times the invention was ascribed to the poet Simonides, perhaps for no other reason than that the strength of his memory was famous. Cicero, who attaches considerable importance to the art, but more to the principle of order as the best help to memory, speaks of Carneades (or perhaps Char brilliant, and modified forms of it survived to Muslim times.
His cult naturally spread with the Persian conquests, and in particular, he reached the Euphrates valley, where he was so long settled that several Greek and Roman writers speak of him as an Assyrian god. Another branch of his cult, of some impor tance for later developments, was established in Cilicia; but for some reason he never penetrated to the western parts of Asia Minor till late times, about the beginning of the Christian era. Naturally, the concept of him was modified by contact with foreign cults, and in particular, he tended to be identified, or at least brought into close association with, the Sun. Perhaps as a result of the accretion of foreign worshippers, his cult took on, if it did not already possess, the form of a mystery, with more or less definite grades of initiation and ceremonials of purification, penance and so forth, appropriate to such a worship.
Mithraism was first transmitted to the Roman world during the 1st century B.C. by the Cilician pirates captured by Pompey.
As late as the time of Augustus it was but little known in Roman territory, and gained a firm foothold in Italy only gradually, as a result of Rome's increasing hold upon Asia.
Towards the close of the 2nd century the cult had begun to spread rapidly through the army, the mercantile class, slaves and actual propagandists, all of which classes were largely corn posed of Asiatics. It throve, especially among military posts, and in the track of trade, notably at ports. The German frontiers afford most evidence of its prosperity. Rome itself was a favour ite seat of the religion. From the end of the 2nd century the emperors encouraged Mithraism, because of the support which it afforded to the divine right of monarchs. The Persian belief that the legitimate sovereign reigned by the grace of Ormazd, whose favour was made manifest by the sending of the Hvaren5, a kind of celestial aureole of fire, resulted in the doctrine that the sun was the giver of the Hvarend. Mithras, identified with Sol In victus, thus became the giver of authority and victory to the imperial house.
The beginning of the downfall of Mithraism dates from A.D. 275, when Dacia was lost to the empire. The aggression of Christianity also was now more effective. The emperors, however, favoured the cult, which was the army's favourite until Constantine de stroyed its hopes. The reign of Julian and the usurpation of Eugenius renewed the hopes of its devotees, but the victory of Theodosius (394) may be considered the end of its existence. It still survived in certain cantons of the Alps in the 5th century, and clung to life with more tenacity in its Eastern home.
Sources, Remains, Ritual.—The sources of present know ledge regarding Mithraism consist of the Vedas, the Avesta, the Pahlevi writings, Greek and Latin literature and inscriptions, and the cult monuments. The last include (a) some hundreds of sculptures, (b) numerous chapels, which are grottoes (spelaea) underground, or imitations thereof in masonry. The average grotto held from fifty to a hundred persons. The size of the sanctuaries, however, was compensated for by their number.