Charles Buck Theological Dictionary 
A religious order; in some places called Jacobins, and in other Predicants, or preaching friars. The Dominican take their name from their founder, Dominic de Guzman, a Spaniard, born in 1170, at Calaroga, in Old Castile: he was first canon and archdeacon of Ossuna; and afterwards preached with great zeal and vehemence against the Albigenses in Languedoc, where he laid the first foundation of his order. It was approved of in 1215, by Innocent III. and confirmed in 1216, by a bull of Honorius III. under the title of St. Augustin; to which Dominic added several austere precepts and observances, obliging the brethren to take a vow of absolute poverty, and also the title of preaching friars, because public instruction was the main end of their institution, and to abandon entirely all their revenues and possessions. The first convent was founded at Thoulouse, by the bishop thereof and Simon de Montfort.
Two years afterwards they had another at Paris, near the bishop's house; and some time after, a third in the Rue St. Jaques, (St. James's street, ) whence the denomination of Jacobins. Just before his death, Dominic sent Gilbert de Fresney, with twelve of the brethren, into England, where they founded their first monastery at Oxford, in the year 1221, and soon after another at London. In the year 1276, the mayor and aldermen of the city of London gave them two whole streets, by the river Thames, where they erected a very commodious convent; whence that place is still called Blackfriars, from the name be which the Dominicans were canned in England. St. Dominic at first only took the habit of the regular canons; that is, a black cassock and rochet: but this he quitted, in 1219, for that which they have ever since worn, which, it is pretended, was shown by the Blessed Virgin herself to the beatified Renaud d'Orleans. This order has been diffused throughout the whole known world. They reckon three popes of this order, above sixty cardinals, several patriarchs, a hundred and fifty archbishops, and about eight hundred bishops, besides masters of the sacred palace, whose office has been constantly discharged by a religious of this order ever since St. Dominic, who held it under Honorius III. in 1218. Of all the monastic orders, none enjoyed a higher degree of power and authority than the Dominican friars, whose credit was great, and their influence universal.
But the measures they used in order to maintain and extend their authority were so perfidious and cruel, that their influence began to decline towards the beginning of the sixteenth century. The tragic story of Jetzer, conducted at Bern, in 1509, for determining an uninteresting dispute between them and the Franciscans, relating to the immaculate conception, will reflect indelible infamy on this order. In order to give the reader a view of the impious frauds which have sometimes been carried on in the church of Rome, we shall here insert an account of this stratagem. The Franciscans maintained that the Virgin Mary was born without the blemish of original sin; the Dominicans asserted the contrary. The doctrine of the Franciscans, in an age of darkness and superstition, could not but be popular; and hence the Dominicans lost ground from day to day. To support the credit of their order, they resolved, at a chapter held at Vimpsen, in the year 1504, to have recurse to fictitious visions and dreams, in which the people at that time had an easy faith; and they determined to make Bern the scene of their operations. A person named Jetzer, who was extremely simple, and much declined to austerities, and who had taken their habit as a lay-brother, was chosen as the instrument of the delusions they were contriving.
One of the four Dominicans, who had undertaken the management of this plot, conveyed himself secretly into Jetzer's cell, and about midnight appeared to him in a horrid figure, surrounded with howling dogs, and seeming to blow fire from his nostrils, by the means of a box of combustibles which he held near his mouth. In this frightful form he approached Jetzer's bed, told him that he was the ghost of a Dominican, who had been killed at Paris, as a judgment of Heaven for laying aside his monastic habit; that he was condemned to purgatory for this crime; adding, at the same time, that by his means he might be rescued from his misery, which was beyond expression. This story, accompanied with horrible cries and howlings, frighted poor Jetzer out of the little wits he had, and engaged him to promise to do all that was in his power to deliver the Dominican from his torment. Upon this the impostor told him, that nothing but the most extraordinary mortifications, such as the discipline of the whip, performed during eight days by the whole monastery, and Jetzer's lying prostrate in the form of one crucified in the chapel during mass, could contribute to his deliverance. He added, that the performance of these mortifications would draw down upon Jetzer the peculiar protection of the Blessed Virgin; and concluded by saying, that he would appear to him again, accompanied with two other spirits.
Morning was no sooner come, than Jetzer gave an account of this apparition to the rest of the convent, who all unanimously advised him to undergo the discipline that was enjoined him, and every one consented to bear his share of the task imposed. The deluded simpleton obeyed, and was admired as a saint by the multitudes that crowded about the convent; while the four friars that managed the imposture magnified, in the most pompous manner, the miracle of this apparition in their sermons, and in their discourses. The night after, the apparition was renewed with the addition of two impostors, dressed like devils, and Jetzer's faith was augmented by hearing from the spectre all the secrets of his life and thoughts, which the impostors had learned from his confessor. In this and some subsequent scenes (the detail of whose enormities, for the sake of brevity, we shall here omit) the impostor talked much to Jetzer of the Dominican order, which he said was peculiarly dear to the Blessed Virgin: he added, that the Virgin knew herself to be conceived in original sin; that the doctors who taught the contrary were in purgatory; that the Blessed Virgin abhorred the Franciscans for making her equal with her Son; and that the town of Bern would be destroyed for harbouring such plagues within her walls.
In one of these apparitions Jetzer imagined that the voice of the spectre resembled that of the prior of the convent, and he was not mistaken; but, not suspecting a fraud, he gave little attention to this. The prior appeared in various forms, sometimes in that of St. Barbara, at others in that of St. Bernard: at length he assumed that of the Virgin Mary, and, for that purpose, clothed himself in the habits that were employed to adorn the statue of the Virgin in the great festivals. the little images, that on these days are set on the altars, were made use of for angels, which, being tied to a cord that passed through a pulley over Jetzer's head, rose up and down, and danced about the pretended Virgin to increase the delusion. The Virgin, thus equipped, addressed a long discourse to Jetzer, in which, among other things, she told him that she was conceived in original sin, though she had remained but a short time under that blemish. She gave him, as a miraculous proof of her presence, a host, or consecrated wafer, which turned from white to red in a moment; and after various visits, in which the greatest enormities were transacted, the Virgin-prior told Jetzer that she would give him the most affecting and undoubted marks of her Son's love, by imprinting on him the five wounds that pierced Jesus on the cross, as she had done before to St. Lucia and St. Catharine. Accordingly she took his hand by force, and struck a large nail through it, which threw the poor dupe into his greatest torment.
The next night this masculine virgin brought, as he pretended, some of the linen in which Christ had been buried, to soften the wound; and gave Jetzer a soporific draught, which had in it the blood of an unbaptized child, some grains of incense and of consecrated salt, some quicksilver, the hairs of the eye- brows of a child; all which, with some stupifying and poisonous ingredients, were mingled together by the prior with magic ceremonies, and a solemn dedication of himself to the devil in hope of his succour. The draught threw the poor wretch into a sort of lethargy, during which the monks imprinted on his body the other four wounds of Christ in such a manner that he felt no pain. When he awakened, he found, to his unspeakable joy, those impressions on his body, and came at last to fancy himself a representative of Christ in the various parts of his passion. He was, in this state, exposed to the admiring multitude on the principal altar of the convent, to the great mortification of the Franciscans. The Dominicans gave him some other draughts, that threw him into convulsions; which were followed by a pipe into the mouths of two images, one of Mary, and another of the child Jesus, the former of which had tears painted upon its cheeks in a lively manner.
The little Jesus asked his mother, by means of this voice (which was that of the prior's, ) why she wept? and she answered, that her tears were owing to the impious manner in which the Franciscans attributed to her the honour that was due to him, in saying that she was conceived and born without sin. The apparitions false prodigies and abominable stratagems of these Dominicans were repeated every night; and the matter was at length so grossly over-acted, that, simple as Jetzer was, he at last discovered it, and had almost killed the prior, who appeared to him one night in the form of the Virgin with a crown on her head. The Dominicans fearing, by this discovery, to lose the fruits of their imposture, thought the best method would be to own the whole matter to Jetzer, and to engage him, by the most seducing promises of opulence and glory, to carry on the cheat. Jetzer was persuaded, or at least appeared to be so. But the Dominicans suspecting that he was not entirely gained over, resolved to poison him; but his constitution was so vigorous, that, though they gave him poison five several times, he was not destroyed by it. One day they sent him a loaf prepared with some spices, which, growing green in a day or two, he threw a piece of it to a wolf's whelps that were in the monastery, and it killed them immediately.
At another time they poisoned the host, or consecrated wafer; but, as he vomited it up soon after he had swallowed it, he escaped once more. In short, there were no means of securing him, which the most detestable impiety and barbarity could invent, that they did not put in practice: till finding at last, an opportunity of getting out to the convent, he threw himself into the hands of the magistrates, to whom he made a full discovery of this infernal plot. The affair being brought to Rome, commissaries were sent from thence to examine the matter; and the whole cheat being fully proved, the four friars were solemnly degraded from their priesthood, and were burnt alive on the last day of May, 1509. Jetzer died some time after at Constance, having poisoned himself, as was believed by some. Had his life been taken away before he had found an opportunity of making the discovery already mentioned, this execrable and horrid plot, which in many of its circumstances was conducted with art, would have been handed down to posterity as a stupendous miracle. The Dominicans were perpetually employed in stigmatizing with the name of heresy numbers of learned and pious men; in encroaching upon the rights and properties of others, to augment their possessions; and in laying the most iniquitous snares and stratagems for the destruction of their adversaries. They were the principal counsellors by whose instigation and advice Leo X. was determined to the public condemnation of Luther. The papal see never had more active and useful abettors than this order, and that of the Jesuits.
The Nuttall Encyclopedia 
A religious order of preaching friars, founded at Toulouse in 1215 by St. Dominic, to aid in the conversion of the heretic Albigenses to the faith, and finally established as the order whose special charge it was to guard the orthodoxy of the Church. The order was known by the name Black Friars in England, from their dress; and Jacobins in France, from the street of Paris in which they had their head-quarters.
Cyclopedia of Biblical, Theological and Ecclesiastical Literature 
Bibliography Information McClintock, John. Strong, James. Entry for 'Dominicans'. Cyclopedia of Biblical, Theological and Ecclesiastical Literature. https://www.studylight.org/encyclopedias/eng/tce/d/dominicans.html. Harper & Brothers. New York. 1870.