CATULLUS

pleasant spring,' he says, 'I played enough at rhyming.' In Rome he mingled with the best society, becoming intimate with the two Ciceros, the Metelli, Hortensius, and probably with Lucretius. And in Rome he met the lady whom, under the name of Lesbia, he has sung in verses which stand at the head of the lyric poetry of passion. It is almost certain that the Lesbia of Catullus was none other than Clodia, the sister of Cicero's enemy, Publius Clodius Pulcher. One of the most beautiful and accomplished women of her time, she inspired Catullus with a passionate love of which the changing phases are mirrored in a wonderful cycle of poems. There is first a time of rapturous joy; then come doubts, quarrels, and reconciliations, and in the end betrayal and despair. The final rupture seems to have happened in 57 B.C., and in that year Catullus accompanied the proprætor Gaius Memmius to his province of Bithynia. He returned to Rome disappointed in his hopes of enriching himself, and entered impetuously into the contest which was then being waged between the senatorian and the democratic parties. Like Cicero and most of the men of letters of his day, he espoused the cause of the senate. A fiery, unscrupulous partisan, he assailed his enemies with equal scurrility and wit, and directed one of his coarsest lampoons at the head of Julius Cæsar. His closing years were darkened by the loss of a favourite brother, on whose tomb in the Troad, which he visited when returning from Bithynia, he wrote one of the most exquisite of all poems that breathe regret for the dead. He was himself cut off in early life, for, though the exact date of his death can only be conjectured, in all probability he did not survive the year

54 B.C.

The extant works of Catullus comprise 116 pieces, many of which are extremely brief, while the longest of them contains only some 400 lines. There is considerable variety, however, in this somewhat slender body of poetry. There are graceful, playful verses of society, and there are verses, struck out in the heat of party warfare, in which satiric wit sparkles through fescennine raillery. There are elaborate descriptive and mythological pieces, such as the Coma Berenices and the stately and richly-coloured Peleus and Thetis, which appear to have been translated or adapted from the Greek. There is the Atys, a strange poem, unlike any other work of a Latin writer in its wild imaginative power and in the magnificent sound and sweep of its galliambic verse. And there is the crowning series of love-poems, in which the incarnation of burning passion in exquisite language, the mastery of verbal music, are carried to what is seemingly the highest attainable point of perfection. In these Lesbia poems' there is no sign of the laborious art which produced the mosaic-work of the Horatian odes. They seem to have flowed forth-thought, feeling, phrase, and cadence combined in a perfect whole at a single creative impulse. Their author's mastery of the Latin tongue was unerring and unbounded. In his works it seems endowed with the elastic and radiant strength of the Greek. He revealed all it had of energy, sonority, and sweetness, of monumental dignity and laughing grace. He moulded it into lines which neither Lucretius nor Virgil has surpassed for majesty of rhythm; he wove it into lyrics which for lightness of movement and caressing sweetness of cadence are unmatched in all the fields of Latin verse. For breadth of vision, fertility of thought, insight into human character, we must turn to other writers than Catullus. For fire and music and unlaboured felicity of phrase he has no superior among the lyric poets of all time.

The text of the works of Catullus, after having been lost for more than three hundred years, was discovered in the 14th century at Verona. The original manuscript was again lost, and until lately only one copy of it, which was preserved at St Germains, and is now in Paris, was believed to be in existence. A manuscript in the Bodleian Library, however, has been discovered by Dr Bährens to be a sister copy of the St Germains manuscript. A commentary on Catullus was issued by Doering in 1788-92. The best editions are those of Mr Robinson Ellis (1866-67), and Bähren's (Leip. 1876-85). Among the English verse translations may be mentioned those of Martin (1861), Cranstoun (1867), and Ellis (1867, and 1871). See R. Ellis's edition, mentioned above, and its admirable commentary (1876); Munro's Criticisms and Elucidations of Catullus (1878); and Sellar's Roman Poets of the Republic (new ed. 1881).

Caub, a town in the Prussian province of HesseNassau, on the right bank of the Rhine, 30 miles WNW. of Wiesbaden by rail. Here Blücher crossed the Rhine with his army, January 1, 1814; and here, too, till 1866, toll was levied by the Duke of Nassau-the only ruler who kept up this feudal has underground slate-quarries; and opposite, on privilege-from vessels navigating the Rhine. Caub an island in the river, where Louis le Débonnaire died in 840, is a castle called the Pfalz, built in 1326, which is said to have been resorted to for safety by the Countesses Palatine during childbed. In 1876 and 1879 Caub was the scene of two serious landslips. Pop. 2179.

which, after a northerly course of 600 miles, falls Cauca, a river of Colombia, in South America, into the Magdalena. Its valley is one of the richest and most populous districts of the continent, and it gives name to the largest of the Colombian states, traversed by the Andean coast-range, and extending along the Pacific from Panama to Ecuador. Area, 260,000 sq. m.; pop. (1887) stated at 435,690. It is rich in minerals, and possesses the most productive platinum mine in America. Capital, Popayán.

Caucasus and the Caucasians. The great mountain-range of the Caucasus forms the backbone of a well-marked geographical region, nearly corresponding with the Russian governor-generalship or lieutenancy of Caucasia. The natural and administrative northern limit is the great Manitch depression, extending from the Sea of Azov to the Caspian, and including the basins of the Kuban and Terek rivers. The southern natural limit is along the basins of the Rion and Kur rivers. The Russian province comprises all the Russian territory to the Turkish and Persian froutiers, including also part of the Armenian highlands and the mountain masses adjoining them, now known by the infelicitous name of Little Caucasus, south of the Rion and Kur rivers. Little or Anti-Caucasus is connected with Caucasus proper by the narrow Mesk ridge crossing the Rion-Kur Valley between the headwaters of those streams. The Sea of Azov and the Caspian seem at one time to have been connected by the Manitch depression; south_of which extend vast steppes of flat treeless landfertile, but with little or no water. South of the steppe to the northern spurs of the mountains is luxuriant park land covered with magnificent grasses, and also quite level. Beyond this rise the mountains in successive terraces. On the south side, towards the Rion and Kur, the mountain face is much steeper and more sudden.

The Caucasus occupies the isthmus between the Black Sea and the Caspian, its general direction being from west-north-west to east-south-east.

From the peninsula of Taman on the Black Sea, to the peninsula of Apsheron on the Caspian, it has a length of about 750 miles. The breadth, including the secondary ranges and spurs, is about 150 miles, but that of the higher Caucasus does not exceed 70 miles. This range is sometimes treated as part of the boundary line between Europe and Asia, but the region is really Asiatic in character (see ASIA), The higher and central part of the range is formed of parallel chains, not separated by deep and wide valleys, but remarkably connected by elevated plateaus, which are traversed by narrow fissures of extreme depth. The highest peaks are in the most central ridge or chain, at least six of them well over 16,000 feet, much exceeding the highest Alps. Mount Elburz attains an elevation of 18,000 feet above the sea; Kazbek reaches a height of more than 16,500 feet; and between these come Koshtantau and Dikh-tau. Here the line of perpetual snow is between 10,000 and 11,000 feet high; but the whole amount of perpetual snow is not great, nor are the glaciers very large or numerous. For more than 100 miles' length of the main ridge there are no passes lower than 10,000 feet. The central chain, in its highest part at least, is granitic or even pure granite. On either side of the granitic axis are metamorphic rocks, such as mica-schists and tale-schists; and beyond these, clay-slates and schists. The secondary parallel chains on both sides of the central ridge are of limestone. The spurs and outlying mountains or hills are of less extent and importance than those of almost any other mountain-range of similar magnitude, subsiding as they do until they are only about 200 feet high along the shores of the Black Sea. Some parts are entirely destitute of wood, but other parts are very densely wooded, and the secondary ranges near the Black Sea exhibit most magnificent forests of oak, beech, ash, maple, and walnut; grain is cultivated in some parts to a height of 8000 feet, while in the lower valleys rice, tobacco, cotton, indigo, &c. are produced. As might be expected from the geographical situation of the Caucasus, the climate, though it is generally healthy, is very different on the northern and southern sides, the vine growing wild in great abundance on the south, which is not the case on the north. The south declivity of the mountains towards Georgia presents much exceedingly beautiful and romantic scenery.

There are no active volcanoes in Mount Caucasus, but every evidence of volcanic action. Elburz and Kazbek are both of volcanic origin. There are hot springs and mud volcanoes at each end of the range, and there are also famous petroleum wells in the peninsula of Apsheron (see BAKU). Mineral springs also occur in many places, notably at Vladikavkaz. The bison, or aurochs, is found in the mountains; bears, wolves, and jackals are among the carnivorous animals. Lead, iron, sulphur, coal, and copper are found.

The waters of the Caucasus flow into four principal rivers the Kuban and the Rion or Faz (the Phasis of the ancients), which flow into the Black Sea; and the Terek and the Kur, which flow into the Caspian. Kuban and Terek are north, Rion and Kur or Kura south of the mountains. The Russians have with great labour carried a military road through a valley somewhat wider than most of the Caucasian valleys. This is the tremendous fissure or ravine of the Dariel gorge about halfway from the Black Sea to the Caspian. The road passes over a height of about 8000 feet, and is protected by many forts. The only other road is by the Pass of Derbend, near the Caspian Sea. There is a railway from Baku by Tiflis to Poti and Batoum; Vladikavkaz is the terminus of the railway from the north.

ČAUCASIAN was the name adopted by Blumen

bach (q.v.) for one of his main ethnological divisions of mankind; and as the Georgian skull he had was the finest in his collection, the Caucasian was taken as the finest type of the Indo-European stock. Subsequent ethnologists have, mainly on philological grounds, broken up the Caucasian variety of Blumenbach into two well-marked philological groups, the Aryan (q.v.) and the Semitic peoples (q.v.). The name Caucasian was clearly a misnomer when it suggested affinity in blood or in language between the very various races of the Caucasus, classified below, and Aryans or Semites; and Prichard and others proposed actually to connect most of the Caucasus peoples with the Mongolian races of Asia. Later anthropologists, finding the word convenient, use Caucasian or Caucasic for the Fair type of man as opposed to the Mongolic or Yellow type. But they distinctly repudiate any suggestion of community of race or of language between the peoples so named; and desire to indicate a physical fact and an anthropological type. See ETHNOLOGY; also PHILOLOGY.

The Caucasus has been called the Mountain of Languages from the multiplicity of tongues spoken in this narrow area-tongues many of them totally distinct from one another, and, with one exception, apparently unconnected with the languages of any other part of the globe, or race of men; though both Aryan and Turkoman affinities have been alleged for Georgian, and Sayce has suggested that the ancient Hittites (q.v.), whose empire in Asia Minor rivalled that of the Assyrians, were of the same stock. There are certain well-marked groups amongst them, within which manifest affinity prevails. (1) The Southern division or Kartveli stock comprises the Georgians or Grusians, mainly in the upper and middle basin of the Kur; the Imeritians, west of the watershed between the Kur and Rion; the Mingrelians, farther west reaching to the Black Sea; the Gurians, south of the Rion; the Laz, on the Turkish frontiers; and the Svans or Suanetians, between the Mingrelians and the higher Caucasus. (2) The Western division contains the Tcherkess or Circassian race, formerly on the left bank of the Kuban, north of Caucasus; the Abkhasians in the narrow strip of land between the Caucasus and the Black Sea on the south; and the Kabards, north and east of Elburz. (3) The Eastern division contains the Chechenz or Tchetchens on the northern slopes of the Eastern Caucasus down to the Terek; and the Lesghians farther east and south. It is doubtful whether the numerous small tribes called Lesghians have any affinity with the Tchetchens, or how far they are related to one another; only one, the Avars, have a written language, and they use Arabic characters. (4) The Ossetes or Ossetians in the centre of Caucasus, on both slopes about Kazbek, are unquestionably a race of the Aryan stock, and the language has affinity with the Persian branch; they call themselves Irun (probably meaning Aryan). The Kartveli group may contain 850,000 persons; the Western group, 130,000; the Eastern, 520,000; the Ossetian, 120,000. All the Caucasian languages are extremely harsh. Some of them are partially inflectional; all save the Ossetian are substantially agglutinative.

In various portions of this territory there are of course other intrusive elements of population of foreign race: Russian Slavs; Tartars; numerous Armenians; Kurds; Greeks; Tats and other Iranians or Tajiks; and a German colony from Würtemberg, east of Tiflis. Not merely do the inhabitants of the Caucasus differ widely in race, but they represent great variety of stages of culture, from the indolent, music-loving Georgians to the

CAUCHY

wild and semi-barbarous Suanetians.

Christianity is the faith of some races, as the Georgians and Ossetes; Mohammedanism of a fanatical type that of others, as the Lesghians; while primitive pagan superstitions seem largely to underlie both religious professions. One Kartvelian tribe, the Khevsurs, has in some measure combined Christianity with Moslem usages.

The resistance which the Caucasian peoples for more than half a century offered to the arms of Russia attracted to them the attention of the world. But with the capture in 1859 of Shamyl, the prophet chief of the Lesghians, who for more than twenty years withstood the armies sent against him, the power of the Caucasians was shattered; by 1870 it was completely broken. The bulk of the Circassians migrated to Turkish territories in Asia or Europe; most of the Abkhasians have done the like. The ancient divisions of the country, Georgia, Imeritia, Svanetia, Mingrelia, &c., were based on tribal distinctions. These have disappeared from the Russian administrative system. According to the latter, the main range of Caucasus divides the province into Ciscaucasia, north of the mountains, and Transcaucasia to the south of them; the former comprising the governments of Stavropol, Kuban, Terek; the latter, those of Daghestan (really north of Caucasus), Sakatal, Tiflis, Kutaïs, Sukhum, Black Sea, Elisabetpol, Baku, and Erivan. Add Batoum and Kars (Russian Armenia), and the Transcaspian territory, and then Caucasia in the widest sense has an area of 308,000 sq. m., and a pop. of 6,290,000. The chief town in Ciscaucasia is Vladikavkaz; in Transcaucasia, Tiflis; the two connected by the great military road through the Caucasus. The old capital of Georgia was Mtzkhet, a good specimen of a Georgian word. For Caucasus and Caucasia, see the map of Russia and the_articles, in this work, CIRCASSIANS, GEORGIA, TRANSCAUCASIA, and, for the wars with Russia, SHAMYL; also Freshfield, Travels in Central Caucasus (1869); Cuninghame, Eastern Caucasus (1872); Bryce, Transcaucasia (1878); Phillipps-Wolley, Savage Svanetia (1883); Dingelstedt on Caucasian Idioms' in Scottish Geographical Magazine (1888); Mourier, Contes et Légendes du Caucase (1888).

་

Cauchy, AUGUSTIN LOUIS, mathematician, born in Paris, 21st August 1789, published in 1815 a Mémoire sur la Théorie des Ondes, which was afterwards made the basis of the undulatory theory of light. Between 1820 and 1830 he wrote several important treatises; and at Prague, where he resided as tutor to the Comte de Chambord, he published his Mémoire sur la Dispersion de la Lumière (1837). From 1848 to 1852 he was professor of Astronomy at Paris, but refused the oath of allegiance to Napoleon III., and lived in retirement till his death, 23d May 1857. A reissue of his works, in 26 vols., was commenced by the Academy in 1882. See his Life by Valson (2 vols. Paris, 1868). Caucus, a private meeting of politicians to agree upon candidates to be proposed for an ensuing election, or to fix the business to be laid before å general meeting of their party. The term origin ated in America, where the caucus has taken fast root, the ticket,' or list of candidates for federal, state, and municipal offices, being always decided upon by the party leaders; but of late years the system has been introduced into England, and adopted by the Radicals, especially in Birmingham, though the word is there used rather for the regularly constituted party organisation. In Notes and Queries for 1885 there is a long discussion as to the origin of the word, which Sydney Smith used in 1818, and John Adams in 1763. Professor Skeat is inclined to refer it to an Indian source, Captain

John Smith (1609) having Cawcawwassoughes for the Indian councillors of Virginia, and Caucorouse for an Indian captain.

Cauda-galli Grit, the basement subdivision of the Devonian system of North America. The forms of a common fossil, supposed to be a seaweed. name (lit. 'cock's tail') is derived from the feathery

Caudebec, two places in the French department of Seine-Inférieure. Caudebec les Elbeuf, 12 miles S. by W. of Rouen, has a pop. (1886) of Caux, a pretty antique village of 2200 inhabitants, 11,038, and manufactures cloth. Caudebec-enis on the Seine, 31 miles WNW. of Rouen.

Caudine Forks (Furcula Caudina), two high, narrow, and wooded mountain-gorges near the town of Caudium, in ancient Samnium, on the borders of Campanía; noted for the defeat of the Romans in the second Samnite war (321 B.C.). See ROME.

Caul, a portion of the amnion or thin membrane enveloping the foetus, sometimes encompassing the head of a child when born, mentioned here on account of the extraordinary superstitions connected with it from very early ages almost down to the present day. It was the popular belief that children so born would turn out very fortunate, and that the caul brought fortune even to those who purchased it. This superstition was so common in the primitive church, that St Chrysostom inveighed against it in several of his homilies. In

later times midwives sold the caul to advocates at high prices, as an especial means of making them eloquent, and to seamen, as an infallible preservative against drowning (cf. Dickens's David Copperfield). It was also supposed that the health of the person born with it could be told by the caul, which, if firm and crisp, betokened health, but if relaxed and flaccid, sickness or death (Notes cauls were often advertised in the newspapers for and Queries, 1884-86). During the 17th century sale—from £10 to £30 being the prices asked; and so recently as 8th May 1848, there was an advertisement in the Times of a caul to be sold, which ' was afloat with its late owner thirty years in all the perils of a seaman's life, and the owner died at last at the place of his birth.' The price asked was six guineas.

Caulaincourt, ARMAND DE, Duke of Vicenza, a statesman of the French empire, born at Caulaincourt (Aisne), in 1772, early distinguished himself as an officer, was made a general of division in 1805, and shortly after created Duke of Vicenza. Faithful to the last to Napoleon, he was made Minister for Foreign Affairs in 1813, and during the Hundred Days resumed the office, receiving a peerage of France, of which he was deprived after the restoration. He died in Paris, February 19, 1827. See his Souvenirs (1837-40).

Cauliflower, a variety of the common kale or cabbage. It was cultivated by the Greeks and Romans, but was little attended to in England till the end of the 17th century; yet prior to the French Revolution cauliflower formed an article of export from England to Holland, whilst English cauliflower seed is still preferred on the Continent. The deformed inflorescence or heads of the cauliflower only are used. Its cultivation for the supply of Covent Garden and other markets occupies the attention of the market-gardeners of London, Cornwall, Devonshire, and the Channel Islands to a very large extent during winter and spring. It is much more tender than Broccoli (q.v.), and the plants that are reared in August for the purpose of supplying the first crop of the following summer require to be protected under hand-glasses or frames during winter. They require to be freely exposed

to air in mild or comparatively mild weather, but severe frost must be prevented from entering the glasses or frames. From the middle of August to the 24th of that month, make two or three sowings at intervals of three or four days. The plants reared from these sowings are planted out, a certain portion of the strongest under hand-glasses to furnish the earliest crop; and an abundant reserve of the smaller plants are planted a few inches apart in frames, to be planted out finally in the spring in the open ground. To succeed these a sowing may be made in a hotbed in January or February; and again in March and May, plants should be reared for successional crops, these later sowings being made in the open ground. The ground must be rich and the cultivation high to produce cauliflower of first-rate quality; there is some risk, however, in having the ground too rich for the winter crop in the case of severe weather occurring; if the plants are extra luxuriant, they will the more readily succumb to frost.

Caulking, in wood shipbuilding, is the operation of driving oakum or untwisted rope into the seams of the outside planks, or of the deck plank ing, to render them watertight. The quantity thus driven in depends on the thickness of the planking; it varies from 1 to 13 double threads of oakum, with 1 or 2 single threads of spun yarn. The caulker first raims or reems the seam-that is, drives a caulking-iron into it, to widen the seam as much as possible, and close any rents or fissures in the wood; he then drives in a little spun yarn or white oakum with a wood mallet and a caulking chisel, and afterwards a much larger quantity of black or coarse oakum. The fibres are driven in until they form a densely hard mass, which not only keeps out water, but strengthens the planking. The seam is finally coated or payed with hot pitch or resin.

In iron or steel shipbuilding and boilermaking the term covers the operation of driving the edge of one thickness of plating firmly against the other thickness upon which it is superimposed, or to which it is adjacent, thus rendering the joints The tool employed is a specially watertight. formed chisel, struck by a metal hand-hammer; but endeavours have been made to supplant this by steam-driven machines, so far with but indifferent success.

Caulop'teris, a generic name for the stems of certain extinct tree-ferns, which range from the Devonian to the Permian system. They are hollow, and covered with markings similar to the leaf-scars on recent tree-ferns.

Caura, a considerable river of Venezuela, rises among the sierras of the southern frontier, and flows NNW. to the Orinoco. On both sides stretches the territory of Caura (22,485 sq. m.), with immense forests of tonka beans.

Caus, CAULX, or CAULS, SALOMON DE, engineer, born at Dieppe in 1576, was a Protestant, and lived much in England and Germany. He was in the service of the Prince of Wales in 1612, and of the Elector Palatine, at Heidelberg, in 1614–20; but by 1623 he returned to France, and became engineer and architect to the king. He died in Paris, 6th June 1626. At Frankfort in 1615 appeared his Raisons des Forces Mouvantes, &c., a work in which is described an apparatus for forcing up water by a steam fountain, differing only in one detail from that of Della Porta (see STEAMENGINE). There is no reason to suppose that the apparatus ever was constructed; but on the strength of the description, Arago has claimed for De Caus the invention of the steam-engine. See the article DE CAUS in vol. xiv. of the Dict. of National Biography (1888).

CAUSALITY

Causality, or the theory of the relation between cause and effect, is one of the most intricate and important questions of philosophical doctrine. All scientific investigation is occupied with the search for the causes of given events, or for the effects of given causes, and with the generalisation of these into laws of nature. But the nature and ground of the relation between cause and effect are obscure and disputed.

·

The difficulty of the question is largely increased by the uncertain signification of the word cause. Thus the investigation into the cause of things, with which early Greek speculation was occupied, was really an inquiry for the ultimate constituent or element from which the variety of actual existence had proceeded; and from this inquiry the quest for a principle of change or development was only gradually distinguished. The first important step in the direction of clear discussion was made in Aristotle's doctrine of the four causes the material cause, out of which a thing is framed; the formal cause, or the essence or idea of the thing; the efficient or active cause, by final cause or purpose it subserves. These, it is means of which it took its present form; and the to be observed, are not so much causes in the modern sense of the term, as principles which enter into the existence of everything. In modern science the meaning of the term is much more restricted, corresponding in some degree to what Aristotle called the efficient cause. Thus both Bacon and Descartes wished to banish the notion

:

But the notion of

of final cause from the scientific interpretation of nature; and although, in Bacon's own method, science was treated as an inquiry into the form or true nature of things (corresponding thus to Aristotle's formal cause), this notion has had little influence. What Descartes sought, and what science still seeks, is the connection rather than the essence of things; and its ideal is a mechanical interpretation of nature in terms of matter and motion. In modern science cause may therefore be said to mean the explanation of change. To some extent it corresponds with efficient cause has itself undergone a profound Aristotle's efficient cause. modification, which seems to have been carried out alongside of the formulating of the principle of the conservation of energy. The tendency in science has been to replace the notion of power or efficiency by that of order or constant sequence. The genesis and justification of the notion of efficiency are matters of dispute: whether it is an a priori intuition, or derived from the consciousness of the voluntary direction of attention, or from the sensations of innervation and muscular resistance. Both Berkeley and Hume directed a vigorous polemic against the doctrine of power expressed by Locke, as going beyond the observed facts of the motion of bodies, and Hume refused to see in mind any more than in matter anything else than a succession of impressions and ideas. Into the rights of this controversy it is impossible to enter here. But clearness of scientific statement has certainly been gained by the extrusion of the notion of power, and substitution for it of that of regular sequence. It is in following out this view of the physical as distinct from the efficient cause that the term comes to be defined as the aggregate of the conditions or antecedents necessary to the production of the effect: meaning by necessary conditions those conditions without which the effect either would not have existed at all, or would have been different from what it is. In popular language, however, and even in most scientific inquiries, the term cause is restricted to the one or two conditions by the intervention of which amongst other more permanent conditions

CAUSALITY

the effect is produced. Thus it is noticeable that while the former or more complete definition corresponds with that expressly given in J. S. Mill's Logic, his inductive methods are entirely devoted to explaining modes of discovering causes in the narrower or popular signification.

It is in this meaning of the term that science investigates causes. In doing so, it goes on the presupposition that every event or change has a cause. This has been called the Law of Universal Causation, and may be expressed by saying that the explanation of every event is to be found in antecedent conditions. Scientific investigation also presupposes the Law of the Uniformity of Nature, that the same conditions or cause will be followed (at all times and places) by the same effects. The grounds and mutual relation of these two assumptions form the chief subject of controversy in the philosophical theory of causality. It is to Hume that the credit is due of having drawn attention to the difficulties involved in the principle of causation, in such a way as to determine the whole course of subsequent philosophy. All reasoning about matters of fact, he shows all physical science, therefore depends on the relation between cause and effect. Yet, between the cause and the effect there is no discoverable connection. There appears not, through all nature, any one instance of connection which is conceivable by us. All events seem entirely loose and separate. One event follows another; but we never can observe any tie between them. They seem conjoined, but never connected.' Hume's own solution of the difficulty is found in the law of mental association. The mind,' he says, 'is carried by habit upon the appearance of one event to expect its usual attendant, and to believe that it will exist. This connection, therefore, which we feel in the mind, or customary transition of the imagination from one object to its usual attendant, is the sentiment or impression from which we form the idea of power or necessary connection. Nothing further is in the case. When we say, therefore, that one object is connected with another, we mean only that they have acquired a connection in our thoughts, and give rise to this inference by which they became proofs of one another's existence: a conclusion which is somewhat extraordinary, but which seems founded on sufficient evidence.' The conclusion to which Hume is driven is thus that, while all reasoning about matters of fact is founded on the principle of causality, this principle has itself no other basis than the mental tendency to pass from one impression to the idea of another impression previously experienced in conjunction with the former. Hume's solution is thus not sceptical (except as regards the application of causality or any other principle beyond experience), but it is subjective: the connection of things is resolved into a customary succession of ideas. Of the numerous theories of causation put forward since the question was thus opened, the two most important are J. S. Mill's rehabilitation of Hume's doctrine to suit the requirements of scientific investigation, and the opposed doctrine of Kant and his philosophical

successors.

It is characteristic of Mill's doctrine that the principle of causality is made a consequence of the Law of the Uniformity of Nature: the familiar truth that invariability of succession is found by observation to obtain between every fact in nature and some other fact which has preceded it.' This principle, which is assumed in every scientific induction, is itself held to be the generalisation of a wide and uncontradicted experience.

phers and others, as well as Kant, had attempted replies to Hume, contending that causality is an intuitive judgment antecedent to experience. But such a reply remains an arbitrary assertion until it is shown how the causal judgment is connected with experience. In Kant's Critique of Pure Reason this connection is thoroughly investigated; the refutation of Hume is only part or consequence of a complete inquiry into the relation of reason to experience. It was, however, largely Hume's doctrine of causality that led to Kant's new point of view, and to the doctrine that experience is the product of the understanding, the realisation of its a priori forms. It is not the sequence of events in time, Kant holds, that gives rise to the principle of causality; but the pure notion of causality finds its realisation in this time-sequence, in which each event is determined by its antecedent. Kant's doctrine, as thus stated, is in full harmony with the principles and methods of modern science; asserting the principle that every change-i.e. each successive state-of the universe is the result of its preceding state, and at the same time leaving to empirical investigation the connection in experience of any one definite thing with any other.

The most important discussions of causality are those of Hume, Treatise of Human Nature, book i. part iii., and Essay Of the Idea of Necessary Connection; Kant, Critique of Pure Reason; and J. S. Mill, System of Logic, book iii. chaps. iii.-v. There is also elaborate treatment of the subject in the works of Reid, Stewart, and Hamilton. Dr Thomas Brown's Inquiry into the Relation of Cause and Effect contains much acute analytical thinking.

Cause Célèbre, a convenient French term for a specially interesting and important legal trial, criminal or civil, such as the Douglas Cause (1769-71), the Dred Scott case in the United States as to the possession of a negro (1856), the Tichborne case (1871-74). There is a great French collection of Causes Célèbres et interessantes (22 vols. 1737-45), by Gayot de Pitaval, with modern continuations. See TRIALS.

and informal essay on any subject in a newspaper Causerie, a name applied to a somewhat short or magazine. More familiar in manner and slighter in structure than the formal essay as usually understood, it is an excellent medium for a writer whose personality interests the reader as much as the value of his thoughts. The name owes its literary currency mainly to the famous Causeries du Lundi of Sainte-Beuve; hardly less valuable examples were many of the occasional essays in the later manner of Matthew Arnold.

Caustic (Gr., burning'), in Medicine and in Chemistry, is the term applied to such substances as exert a corroding or disintegrating action on the skin and flesh. Lunar caustic (so called because silver was called luna, 'the moon,' in the alchemists' mystical jargon) is nitrate of silver, and common caustic is potash. When used as a caustic in medicine, the substance is fused and cast into moulds, which yield the caustic in small sticks the thickness of an ordinary lead pencil, or rather less.Caustic is also used in chemistry in an adjective sense-thus caustic lime, or pure lime, CaO, as distinguished from mild lime, or the carbonate of lime, CaCO3, caustic magnesia, MgO, and mild magnesia, MgCO,, caustic potash, caustic soda (for these, see POTASH, SODA, &c.). See CAUTERY.