Quotations from Chapter 28 of Edward Gibbon's History of the Decline and Fall of the Roman Empire ("Final Destruction of Paganism; Introduction of the Worship of Saints and Relics among the Christians (378-420 A.D.)"):
A small number of temples was protected by the fears, the venality, the taste, or the prudence of the civil and ecclesiastical governors. The temple of the Celestial Venus at Carthage, whose sacred precincts formed a circumference of two miles, was judiciously converted into a Christian church; and a similar consecration has preserved inviolate the majestic dome of the Pantheon at Rome. But in almost every province of the Roman world, an army of fanatics, without authority and without discipline, invaded the peaceful inhabitants; and the ruin of the fairest structures of antiquity still displays the ravages of those barbarians who alone had time and inclination to execute such laborious destruction.
At that time the archiepiscopal throne of Alexandria was filled by Theophilus, the perpetual enemy of peace and virtue; a bold, bad man, whose hands were alternately polluted with gold and with blood.
The valuable library of Alexandria was pillaged or destroyed; and near twenty years afterwards, the appearance of the empty shelves excited the regret and indignation of every spectator whose mind was not totally darkened by religious prejudice. The compositions of ancient genius, so many of which have irretrievably perished, might surely have been excepted from the wreck of idolatry, for the amusement and instruction of succeeding ages; and either the zeal of the avarice of the archbishop might have been satiated with the rich spoils which were the reward of his victory.
As the objects of religion were gradually reduced to the standard of the imagination, the rites and ceremonies were introduced that seemed most powerfully to affect the senses of the vulgar. If, in the beginning of the fifth century, Tertullian, or Lactantius, had been suddenly raised from the dead, to assist at the festival of some popular saint or martyr, they would have gazed with astonishment and indignation on the profane spectacle which had succeeded to the pure and spiritual worship of a Christian congregation. As soon as the doors of the church were thrown open, they must have been offended by the smoke of incense, the perfume of flowers, and the glare of lamps and tapers, which diffused, at noon-day, a gaudy, superfluous, and, in their opinion, a sacrilegious light. If they approached the balustrade of the alter, they made their way through the prostrate crowd, consisting, for the most part, of strangers and pilgrims, who resorted to the city on the vigil of the feast; and who already felt the strong intoxication of fanaticism, and, perhaps, of wine. Their devout kisses were imprinted on the walls and pavement of the sacred edifice; and their fervent prayers were directed, whatever might be the language of their church, to the bones, the blood, or the ashes of the saint, which were usually concealed, by a linen or silken veil, from the eyes of the vulgar. The Christians frequented the tombs of the martyrs, in the hope of obtaining, from their powerful intercession, every sort of spiritual, but more especially of temporal, blessings. They implored the preservation of their health, or the cure of their infirmities; the fruitfulness of their barren wives, or the safety and happiness of their children. Whenever they undertook any distant or dangerous journey, they requested that the holy martyrs would be their guides and protectors on the road; and if they returned without having experienced any misfortune, they again hastened to the tombs of the martyrs, to celebrate, with grateful thanksgivings, their obligations to the memory and relics of those heavenly patrons. The walls were hung round with symbols of the favours which they had received; eyes, and hands, and feet, of gold and silver: and edifying pictures, which could not long escape the abuse of indiscreet or idolatrous devotion, represented the image, the attributes, and the miracles of the tutelar saint. The same uniform original spirit of superstition might suggest, in the most distant ages and countries, the same methods of deceiving the credulity, and of affecting the senses of mankind: but it must ingenuously be confessed that the ministers of the catholic church imitated the profane model which they were impatient to destroy. The most respectable bishops had persuaded themselves that the ignorant rustics would more cheerfully renounce the superstitions of Paganism, if they found some resemblance, some compensation, in the bosom of Christianity. The religion of Constantine achieved, in less than a century, the final conquest of the Roman empire: but the victors themselves were insensibly subdued by the arts of their vanquished rivals.
(see also Gibbon _-_Table_of_Contents, Gibbon_-_Thoughts_Upon_Reading, ... and http://www.his.com/~z/gibbon.html for a single-page presentation of Gibbon quotes)
(correlates: GibbonChapter29, Gibbon - Table of Contents, SkippingAhead, ...)