Hallucinations may become frequent, and to a certain extent systematic, especially if a belief in their supernatural origin exists; in which case a person may be for a long period of sound and discriminating understanding, except when in a trance, or beholding a vision.

The visions of St. Theresa have, for three hundred years, formed an important chapter in religious literature, and another in pathology. At twelve she was devoutly pious, becoming so after the death of her mother. About the age of fifteen she fell off into a very worldly state, and against her will was placed by her father in a convent. She was frequently ill, and finally, after a year and a half, owing to a dangerous sickness, returned home. Some time afterward she was seized with a violent fever, and upon recovery determined to devote herself to a religious life, and in opposition to her father's wishes entered a Carmelite convent and took the veil. This was in her twentieth year. Her biographer, as translated by Dr. Madden, says that she was attacked " with frequent fits of fainting and swooning, and a violent pain at her heart, which sometimes deprived her of her senses." Her first trance was in 1537, in her twenty-third year; it lasted for four days, aud during it through excess of pain she bit her tongue in many places—a phenomenon common to fits of various kinds. At last she was reduced almost to a skeleton, had a paralytic affection of her limbs, and remained a cripple for three years. Her first vision was three years later, when she had allowed herself some dissipation of mind. "The apparition of our Lord was suddenly presented to the eyes of her soul, with a rigorous aspect testifying to the displeasure occasioned bv her conduct".

There were great differences of opinion as to the source of her visions. Several very learned priests and confessors judged her to be deluded by the devil. One of them instructed her to make the sign of the cross, and to insult the vision as that of a fiend. In one of her visions, according to her statement, the Lord appeared angry at her instructions, and bade her tell them it was tyranny. She acknowledged that she frequently saw devils in hideous figures, but she drove them away by the cross or by holy water. She also claimed to see St. Joseph, the blessed Virgin, and other saints; had visions of purgatory, and saw a gnat number of souls in heaven who had been there.

There is no difficulty in explaining her visions on natural principles. She was a religious woman, in such a state of health as to be subject to trances, and they took their character from her conventual and other religious instruction. Visions of this kind have been common in the excitable of all sects. The early Methodists had many of them, which Mr. Wesley could not understand; and he expelled some persons from the society because they persisted against his commands in narrating visions which even he could not accept as of divine origin.

Luther suffered from hallucinations of a religious character for a considerable period of his life. The opposition he encountered and his sedentary life, taken in connection with the extraordinary powers attributed to Satan in the middle ages, fully explain his visions. Luther thought that the devil removed a bag of nuts, transformed himself into a fly, hung on his neck, and lay with him in bed. His visions would sometimes come on after nightmare. Here is his own account: " I awoke in the middle of the night. Satan appeared to me. I was seized with horror. I sweated and trembled. My heart beat in a frightful manner. The devil conversed with me. His logic was accompanied by a voice so alarming that the blood froze in my veins".

Zuinglius had a similar experience when he was half asleep. A phantom, black or white, he could not say which, appeared before him, called him a coward, and stirred him Tip to fight. This is explained by Forbes Winslow as a case of overheated sensorium, " during the transient continuance of which the retina became so disturbed as to conjure up a phantom which the patient not only mistook for a reality, but, what is still worse, acted upon his mistaken or diseased imagination".

Swedenborg's visions were of the same class. He was educated, devoted himself for many years to science, and up to his fifty-fourth year had the reputation of a scientific and philosophic student; was a professor in the mineralogical school, and believed to be a simple-minded man of the world. About 1743 he had a violent fever, in which for a little time he was mad, and rushed from the house stark naked, proclaiming himself the Messiah. After that period a change took place in him, and he lived twenty-nine years in the firm conviction that he held continual intercourse with angels and also with deceased human beings. He says that he conversed with St. Paul during the whole year, particularly in reference to the text Romans iii. 28. He asserted that he had conversed three times with St. John, once with Moses, a hundred times with Luther, and with angels daily "for twenty years".

Swedenborg had an elevated style of thought, and when reasoning upon the fundamental principle which underlies his theological views, he is acute and profound. Attention has frequently been called to his shrewdness in explaining why, when he claimed to hear the voices of angels, those who stood by could not, by his declaring that he was accustomed to see and hear angels when perfectly wide awake, and adding : " The speech of au angel or of a spirit sounds like and as loud as that of a man, but it is not heard by the bystauders. The reason is that the speech of an angel, or of a spirit, finds entrance first into a man's thoughts, and reaches his organs of hearing from within." It is necessary only to read his literal statements to perceive the subjective character of the visions. He gives detailed accounts of the habits, form, and dress of the angels. He sends his opponents mostly to Gehenna and sees them there. The chief representatives of the reformed churches go to heaven, but Catholics and some of his Protestant opponents he sees in vision elsewhere.

Visions and hallucinations of men of this class are quoted against each other in the ecclesiastical conflicts of the middle ages, and more lately, as proofs of the doctrines held by them. But as proofs they are mutually destructive, exist in all religions, true or false, and are liable to occur apart from religion. In the revivals which occurred in the early part of this century in the United States, and which sometimes take place now, visions are not infrequently connected with religious experience. When men pray without attending to the necessary cares of the body days and weeks together, the result is faint-ings and trances accompanied by visions. Where they are believed to be of divine origin they produce profound impressions, but there is no reason to think their cause different from those already discussed, nor have unbelievers in Christianity always escaped t hem.

The autobiography of Lord Herbert of Cherbury relates a remarkable vision, which is a noteworthy illustration of inconsistency. Lord Herbert did not believe in the divine origin of Christianity, and wrote a book against the credibility of the accounts of miracles in the Bible. When the manuscript was completed he exhibited it to Grotius and Tilenus, whom he met in France. They praised it much and exhorted him to publish it; but he foresaw that it would encounter opposition, and hesitated for some time. The history of what followed is given in his own words:

One fine day, about noon, my windows being open, I took my book, knelt down, and pronounced aloud these words : "O eternal God, creator of the light which illuminates me, thou who enlightenest souls when thou wouldst, tell me by a celestial sign if I should publish or suppress my work." I had hardly uttered these words than a loud but agreeable sound proceeded from heaven, which impressed me with such great joy that I felt convinced that my request was granted. Howsoever strange this may appear, I protest, before God, not oidy that I heard the sound, but saw, in the clearest sky on which I ever gazed, the spot whence it came. In consequence of this sign I published my book, and spread it throughout all Christian lands, amongst all the learned capable of reading and appreciating it.

This circumstance is of great importance. No doubt has ever been thrown upon the truth of the recital, which shows how a person not subject to hallucinations, under circumstances of deep meditation, or under the influence of strong desire and expectation, may generate an hallucination, which may be the only one that he will experience in the course of a lifetime, and leave no evil effects except the false inferences which, supposing it to be of supernatural origin, he will draw from it. It demonstrates also that the absence or the presence of any particular form of faith is not essential; and it is obvious that Lord Herbert might easily have passed into a state of habitual visions in all respects analogous to those of Swedeuborg or St. Theresa.