a presbyter of the church of Alexandria, celebrated as having given his name to the most extensive and formidable heresy that ever divided the Christian Church. He is supposed to have been a native of Libya, the country which gave birth in the previous century to Sabellius, the heresiarch whose doctrine represented the opposite pole to that of Arius.

It had more than once been decided by the voice of the church, in opposition to Sabellius and other heretics, that there are three distinct persons in the Divine Trinity. But the mutual relation, and the nature of the difference between these persons, had not yet formed a subject of dispute or of decision, and various opinions were held regarding it, without its being considered necessary that a distinct and precise phraseology should be adopted on a point so difficult and mysterious.

It was in the learned and disputatious city of Alexandria that the matter first came to an open controversy. Alexander, the Christian bishop of that city, maintained in an assembly of his presbyters, that the Son of God is not only equal to the Father, but of the same essence (ὁμοούσιος). Arius, who is represented as a man of great learning and eloquence, and of high reputation for sanctity and zeal, opposed his bishop, on the ground that his doctrine was a relapse into the error of Sabellius, and going to the opposite extreme, maintained that the Son was not the same in substance with the Father, but only similar (ἴκεονος), and that, though the highest of all creatures, there was a time when he was not.

The opinions of Arius found many supporters, the most distinguished and influential of whom was Eusebius, bishop of Nicaea, who, being a favourite of Constantia the sister of the emperor, secured for Arius important patronage. Alexander having failed in his attempt to extinguish the heresy by warning and remonstrance, called a council of African bishops at Alexandria (A.D. 321), which condemned the Arian doctrine as blasphemous, and cast the offender out of the church. The heresy, however, continued to spread. The Emperor Constantine, who at first treated the matter as a trifling logomachy, at length found it necessary for the peace of the church to call a general council at the city of Nicaea, in Bithynia, A.D. 325. At this celebrated assembly, composed of 318 bishops from all parts of the Christian world, the doctrine of the consubstantiality of the Son with the Father was, after much discussion, decreed as the orthodox faith of the church, and embodied in a definite formula, which not merely expressed the catholic faith but specially anathematized the Arian doctrine and its supporters as accursed. Arius was banished to Illyricum, his books were ordered to be burned, and capital punishment was denounced against all who should keep them in their possession.

But the heresy was not thus to be extinguished. Arius had powerful friends at court, and his party, though branded with the condemnation of the church, made continual progress. After five years' banishment he was recalled to Constantinople, where he satisfied the unsettled theological judgment of the emperor by a confession of faith so vaguely worded that, without abjuring his own opinions, he seemed Ark of the Covenant.

Ark, Noah's, a floating vessel built by the patriarch Noah, for the preservation of his family, and the several species of animals, during the Deluge. The ark has afforded several points of curious inquiry relating to its form, capacity, materials, &c. The wood of which it was built is called in the Hebrew gopher wood, and in the Septuagint square timbers. Some translate the original cedar, others pine, others box, &c. Pelletier prefers cedar, on account of its incorruptibility and the great abundance of it in Asia. Fuller and Bochart contend that it was built of what the Greeks call κυπαρισσος, or the cypress tree; for, taking away the termination, kypar and gopher differ very little in sound. In what place Noah built and finished his ark is no less a matter of dispute; but the most general opinion is, that it was built in Chaldea, in the territories of Babylon. Its dimensions, as given by Moses, are 300 cubits in length, 50 in breadth, and 30 in height. Dr Arbutnott computes its burthen at 81,062 tons. It contained, besides eight persons of Noah's family, one pair of every species of unclean animals, and seven pairs of every species of clean animals, with provisions for them all during the whole year. The insuperable difficulties connected with the belief that all the existing species of animals were provided for in the ark, are obviated by adopting the suggestion of Bishop Stillingfleet, approved by Matthew Poole, Pye Smith, Le Clerc, Rossermüller, and others, that the Deluge did not extend beyond that region of the earth then inhabited, and that only the animals of that region were preserved in the Ark. See DELUGE, and Kitto's Biblical Cyclopedia.

Ark of the Covenant, a kind of chest, of an oblong shape, made of shittim (acacia) wood, a cubit and a half broad and high, two cubits long, and covered on all sides with the purest gold. It was ornamented on its upper surface with a border of gold; and on each of the two sides were two gold rings, in which were placed the gold-covered poles by which it was carried. The lid or cover of the ark was made of the purest gold. Over it, at the two extremities, were two cherubim, with their faces turned towards each other, and inclined a little towards the lid (or mercy-seat); and their wings spread Arkansas out over the top of the ark.

This sacred object was deposited in the innermost part of the tabernacle, called "the holy of holies," and afterwards in the corresponding apartment of the Temple. Within it were deposited the tables of the law; beside it were preserved a golden pot full of manna, the rod of Aaron, and a copy of the book of the law.

Extreme sanctity attached to the ark, as the material symbol of the Divine presence. During the marches of the Israelites it was covered with a purple pall, and borne by the priests, with great reverence and care, in advance of the host. It is not wonderful therefore that the neighbouring idolaters looked upon it as the God of the Israelites (1 Sam. iv. 6, 7), a delusion which may have been strengthened by the figures of the cherubim on it. After the settlement of the Jews in Palestine, the ark remained in the tabernacle at Shiloh until the time of Eli, when it was carried along with the army in the war against the Philistines, under the superstitious notion that it would secure the victory to the Hebrews. Not only however were they beaten, but the ark itself was taken by the Philistines (1 Sam. iv. 3-11), whose triumph was, however, very short lived, as they were so oppressed by the hand of God, that after seven months they were glad to send it back again. After that it remained apart from the tabernacle at Kirjath-jearim, where it continued until the time of David, who succeeded in effecting its safe removal, in grand procession, to Mount Zion (2 Sam. vi.) When the Temple of Solomon was completed, the ark was deposited in the sanctuary (1 Kings viii. 6-9). What became of it when the Temple was plundered and destroyed by the Babylonians is not known. The Jews believe that it was concealed from the spoilers, and account it among the hidden things which the Messiah is to reveal. It is certain, however, from the consent of all the Jewish writers, that the old ark was not contained in the second temple, and there is no evidence that any new one was made. Indeed the absence of the ark is one of the important particulars in which this temple was held to be inferior to that of Solomon.—See Calmet's Dissertation sur l'Arche d'Alliance.