Progress in scientific research is due largely to provisional explanations which are constructed by imagination, but such hypotheses must be framed in relation to previously ascertained facts and in accordance with the principles of the particular science. In spite, however, of these broad practical considerations, imagination differs fundamentally from belief in that the latter involves “ objective control of subjective activity ” (Stout). The play of imagination, apart from the obvious limitations (e.g. of avoiding explicit'self-contradiction), is conditioned only by the general trend of the mind at a given moment. Belief, on the other hand, is immediately related to practical activity: it is perfectly possible to imagine myself a millionaire, but unless I believe it I do not, therefore, act as such. Belief always endeavours to conform to objective conditions;though it is from one point of view subjective it is also objectively conditioned, whereas imagination as such is specifically free. The dividing line between imagination and belief varies widely in different stages of mental development. Thus a savage who is ill frames an ideal reconstruction of the causes of his illness, and attributes it to the hostile magic of an enemy. In ignorance of pathology he is satished with this explanation, and actually believer in it, whereas such a hypothesis in the mind of civilized man would be treated as a pure effort of imagination, or even as a hallucination. It follows that the distinction between imagination and belief depends in practice on knowledge, social environment, training and the like.
Although, however, the absence of objective restraint, i.e. a certain unreality, is characteristic of imagination, none the less it has great practical importance as a purely ideational activity. Its very freedom from objective limitation makes it a source of pleasure and pain. A person of vivid imagination suffers acutely from the imagination of perils besetting a friend. In fact in some cases the ideal construction is so “ real "' that specific physical manifestations occur, as though imagination had passed into belief or the events imagined were actually in progress.
IMAM, an Arabic word, meaning “leader ” or “ guide ” in the sense of a “pattern whose example is followed, whether for good or bad.” Thus it is applied to the Koran, to a builde'r's level and plumb-line, to a road, to a school-boy's daily task, to a written record. It is used in several of these senses in the Koran, but specifically several times of leaders and (ii. 118) of Abraham, "Lo, I make theea pattern for mankind.” Imamthus became the name of the head of the Moslem community, whose leadership and pattern hood, as in the case of Mahomet himself, is to be regarded as of the widest description. His duty is to be the lieutenant, the Caliph (q.v.) of the Prophet, to guard the faith and maintain the government of the state. Round the origin and basis of his office all controversies as to the Moslem state centre. The Sunnites hold that it is for men to appoint and that the basis is obedience to the general usage of the Moslem peoples from the earliest times. The necessity for leaders has always been recognized, and a leader has always been appointed. The basis is thus agreement in the technical sense (see Mxrromirzoan LAW), not Koran nor tradition from Mahomet nor analogy. The Shi'i1es in general hold that the appointment lies with God, through the Prophet or otherwise, and that He always has appointed. The Kharijites theoretically recognize no absolute need of an Imam; he is convenient and allowable. The Motazilites held that reason, not agreement, dictated the appointment. Another distinction between the Sunnites and the Shiites is that the Sunnites regard the Imam as liable to err, and to be obeyed even though he personally sins, provided he maintains the ordinances of Islam. Effective leadership is the essential point. But the Shi'ites believe that the divinely appointed Imam is also divinely illumined and preserved (mairzim) from sin. The above is called the greater Imamate. The lesser Imamate is the leadership in the Friday prayers. This was originally performed by the Imam in the first sense, who not only led in prayers but delivered a sermon (lfhiij/ni): but with the growth of the Moslem empire and the retirement of the caliph from public life, it was necessarily given over to a deputy-part of a gradual process of putting the Imamate or caliphate into commission. These deputy Imams are, in Turkey, ministers of the state, each in charge of his own parish; they issue passports, &c., and perform the rites of circumcision, marriage and burial. 'In Persia among Shiites their position is more purely spiritual, and they are independent of the state. A few of their leaders are called M ujlalrids, i.e. capable of giving an independent opinion on questions of religion and canon law. A third use of the term Imam is as an honorary title. It is thus applied to leading theologians, eng, to Abu Hanifa, ash-Shaffi, Malik ibn Anas, Ahmad ibn Hanbal (these are called “the four Imams 'i'), Ghazali.
See l/lcG. de Slane's transl. of Ibn KhaldEn's Prolégoménes, i. gif: 5e<l~> 402 Seqy 4?6 Seq-» 445; Ill- 35, 58 seq.; Ostrorog's transllof ~award1's Ahkam 1. 89 seq.; Haa1brucker's transl. of Shahrastani by index; ]uynboll's De Mohammedaanirche ll/el, 316 seq.; Sell's Faith of Islam, 95 seq.; Macdonald's Development of Muslim Theology, 56 Seq. (D. B. MA.)
IMBECILE (through the French from Lat. imbecillus or imbecillis, weak, feeble; of unknown origin), weak or feeble particularly in mind. The term “ imbecility ” is used conventionally of a condition of mental degeneration less profound than “ idiotcy ” (see INSANITY).
IMBREX (Latin for “ tile ”), in architecture the term given to the covering tile of the ancient roof: the plain tile is turned up on each side and the imbrex covers the joint. In the simpler type of roof the imbrex is semicircular, but in some of the Greek temples it has vertical sides and an angular top. In the temple of Apollo at Bassae, where the tiles were in Parian marble, the imbrex on one side of the tile and the tile were worked in one piece out of the solid marble.
IMBROS, a Turkish island in the Aegean, at the southern end of the Thracian Chersonese peninsula. It forms with Samothrace about 17 rn. distant, a caza (or canton) in the sanjak of Lemnos and province of the Archipelago Isles. Herodotus (v. 26) mentions it as an abode of th e historic Pelasgians (q.'v.). It was, like Samothrace, a seat of the worship of the Cabeiri (q.rv.). Theisland is now the seat of a Greek bishopric. There is communication with the mainland by occasional vessels. The island is of great fertility-wheat, oats, barley, olives, sesame and valonia being the principal products, in addition to a variety of fruits. Pop. about Q2,000, nearly all Turks.
IMERETIA, or IMERITIA a district in Russian Transcaucasia extends from the left bank of the river Tskheniz-Tskhali to the Suram range, which separates it from Georgia on the east, and is bounded on the south by Akhaltsikh, and thus corresponds roughly to. the eastern part of the modern government of Kutais. Anciently a part of Colchis, and included in Lazia during the Roman empire, Imeretia was nominally under the dominion of the Greek emperors. In the early part of the 6th century it became the theatre of wars between the Byzantine emperor Iustinian and Chosroes, or Khosrau, king of Persia. Between 7 5o and 98 5 it was ruled by a dynasty (Apkhaz) of native princes, but was devastated by hostile incursions, reviving only after- it became united to Georgia. It flourished until the reign of Queen Thamar, but after her death (1212) the country became impoverished through strife and internal dissensions. It was reunited with Georgia from 1318 to 1346, and again in 1424. But the union only lasted forty-five years; from 1469 until 1810 it was governed by a Bagratid dynasty, closely akin to that which ruled over Georgia. In 1621 it made the earliest appeal to Russia for aid; in 1650 it acknowledged Russian suzerainty and in 1769 a Russian force expelled the Turks. In 1803 the monarch declared himself a vassal of Russia, and in 1810 the little kingdom was definitively annexed to that empire. (See Gizonom.)
IMIDAZOLES, or GL'oxAL1N1:s, organic chemical compounds CH = C H -
containing the ring system HN< CH Imidazole itself was first prepared by H. Dehus(/11111. 1858, 107, p. 254) by the action of ammonia on glyoxal, ZCZHQOQ-l-2lYI*I3=C3H4N2+H¢CO2+2H¢O. The compounds of this series may be prepared by the condensation
of ortho-dike tones with ammonia and aldehvdes