Ignorance of mental philosophy has given rise to many superstitions. Many persons have believed in the real, visible appearance of ghosts, spirits, or apparitions. Yet these things are clearly and satisfactorily explained on the established principles of mental philosophy. And from this source we learn that they exist alone in the mind, in the same manner as do other ideas and images, except in the instances recorded in Scripture. They are caused by some misconception, mental operation, or bodily disorder. We will give a few examples to substantiate this position.

Dr. Ferriar relates the case of a gentleman travelling in the Highlands of Scotland, who was conducted to a bed room which was reported to be haunted by the spirit of a man who had there committed suicide. In the night, he awoke under the influence of a frightful dream, and found himself sitting up in bed with a pistol grasped in his right hand. On looking around the room, he now discovered, by the moonlight, a corpse, dressed in a shroud, reared against the wall, close by the window, the features of the body and every part of the funeral apparel being distinctly perceived. On recovering from the first impulse of terror, so far as to investigate the source of the phantom, it was found to be produced by the moonbeams forming a long, bright image through the broken window.

"Two esteemed friends of mine," says Dr. Abercrombie, "while travelling in the Highlands, had occasion to sleep in separate beds, in one apartment. One of them, having awoke in the night, saw, by the moonlight, a skeleton hanging from the head of his friend's bed, every part of it being perceived in the most distinct manner. He got up to investigate the source of the appearance, and found it to be produced by the moonbeams falling back upon the drapery of the bed, which had been thrown back in some unusual manner, on account of the heat of the weather. He returned to bed, and soon fell asleep. But having awoke again some time after, the skeleton was so distinctly before him, that he could not sleep without again getting up to trace the origin of the phantom. Determined not to be disturbed a third time, he now brought down the curtain to its usual state, and the skeleton appeared no more."

Dr. Dewar relates the case of a lady who was quite blind, and who never walked out without seeing a little old woman, with a crutch and a red cloak, apparently walking before her. She had no illusion when within doors. Dr. Gregory once took passage in a vessel to a neighboring country, to visit a lady who was in an advanced stage of consumption. On his return, he had taken a moderate dose of laudanum, with the view of preventing seasickness, and was lying on a couch, in the cabin, when the figure of a lady appeared before him in so distinct a manner, that her actual presence could not have been more vivid. He was quite awake, and fully sensible that it was a phantom produced by the opiate, in connection with his intense mental feeling; but he was unable by any effort to banish the vision.

A gentleman, mentioned by Dr. Conolly, when in great danger of being wrecked in a boat, on the Eddystone rocks, said he actually saw his family at the moment. In similar circumstances of great danger, others have described the history of their past lives, being represented to them in such a vivid manner, that, at a single glance, the whole was before them, without the power of banishing the impression. We have read the account of a whole ship's company being thrown into the utmost consternation by the apparition of a cook, who had died a few days before. He was distinctly seen walking ahead of the ship, with a peculiar gait, by which he was distinguished when alive, from having one leg shorter than the other. On steering the ship towards the object, it was found to be a piece of floating wreck!

There is a story on record, of a piratical cruiser having captured a Spanish vessel, during the seventeenth century, and brought her into Marblehead harbor, which was then the site of a few humble dwellings. The male inhabitants were all absent on their fishing voyages. The pirates brought their prisoners ashore, carried them at the dead of night into a solitary glen, and there murdered them. Among the captives was an English female passenger. The women who belonged to the place heard her dying outcries, as they rose through the midnight air, and reverberated far and wide along the silent shores. She was heard to exclaim, "O, mercy, mercy! Lord Jesus Christ, save me! save me!" Her body was buried by the pirates on the spot. The same piercing voice is believed to be heard at intervals, more or less often, almost every year, in the stillness of a calm starlight, or clear moonlight night. There is something, it is said, so wild, mysterious, and evidently superhuman in the sound, as to strike a chill of dread into the hearts of all who listen to it. A writer in the Marblehead Register, of April 3, 1830, declares that "there are not persons wanting at the present day, persons of unimpeachable veracity and known respectability, who still continue to believe the tradition, and to assert that they themselves have been auditors of the sounds described, which they declare were of such an unearthly nature as to preclude the idea of imposition or deception." When "the silver moon holds her way," or when the stars are glistening in the clear, cold sky, and the dark forms of the moored vessels are at rest upon the sleeping bosom of the harbor,—when no natural sound comes forth from the animate or inanimate creation but the dull and melancholy note of the winding shore, how often, at midnight, is the watcher startled from the reveries of an excited imagination by the piteous, dismal, and terrific screams of the unlaid ghost of the murdered lady!

Erroneous impressions are often connected with some bodily disease, more especially disease in the brain. Dr. Gregory mentions the case of a gentleman liable to epileptic fits, in whom the paroxysm was generally preceded by the appearance of an old woman in a red cloak, who seemed to come up to him, and strike him on the head with her crutch. At that instant he fell down in the fit. Another is mentioned by Dr. Alderston, of a man who kept a dram shop, and who would often see a soldier endeavoring to force himself into his house in a menacing manner; and in rushing forward to prevent him, would find it a mere phantom. This man was cured by bleeding and purgatives; and the source of this vision was traced to a quarrel which he had had some time before with a drunken soldier. In delirium tremens such visions are common, and assume a variety of forms.

Similar phantasms occur in various forms in febrile diseases. A lady was attended by Dr. Abercrombie, having an affection of the chest. She awoke her husband one night, at the commencement of her disorder, and begged him to get up instantly, saying that she had distinctly seen a man enter the apartment, pass the foot of her bed, and go into a closet that entered from the opposite side of the room. She was quite awake, and fully convinced of the reality of the appearance. But, upon examining the closet, it was found to be a delusion, although it was almost impossible to convince the lady it was not a reality.

A writer in the Christian Observer mentions a lady, who, during a severe illness, repeatedly saw her father, who resided at the distance of many hundred miles, come to her bedside, withdraw the curtain, and talk to her in his usual voice and manner. A farmer, mentioned by the same writer, on returning from market, was deeply affected by an extraordinarily brilliant light, which he saw upon the road, and by an appearance in the light, which he supposed to be our Savior. He was greatly alarmed, and, spurring his horse, galloped home; remained agitated during the evening; was seized with typhus fever, then prevailing in the vicinity, and died in about ten days. It was afterwards ascertained, that on the morning of the same day, before he left home, he had complained of headache and languor; and there can be no doubt, says this writer, that the spectral appearance was connected with the commencement of the fever.

Analogous to this is the very striking case related by a physician, of a relative of his, a lady about fifty. On returning home one evening from a party, she went into a dark room to lay aside some part of her dress, when she saw distinctly before her the figure of death, as a skeleton, with his arm uplifted, and a dart in his hand. He instantly aimed a blow at her with the dart, which seemed to strike her on the left side. The same night she was seized with a fever, accompanied with symptoms of inflammation in the left side, but recovered after a severe illness.

We have read the account of a lady who had an illusion affecting both her sight and hearing. She repeatedly heard her husband's voice calling to her by name, as if from an adjoining room. On one occasion, she saw his figure most distinctly, standing before the fire in the drawing room, when he had left the house half an hour before. She went and sat down within two feet of the figure, supposing it to be her husband, and was greatly astonished that he did not answer her when she spoke to him. The figure continued visible several minutes, then moved towards a window at the farther end of the room, and there disappeared. On another occasion, while adjusting her hair before a mirror, late at night, she saw the countenance of a friend, dressed in a shroud, reflected from the mirror, as if looking over her shoulder. This lady had been for some time in bad health, being affected with a lung complaint, and much nervous debility.

Another case of an illusion of hearing is reported of a clergyman, who was accustomed to full living, and was suddenly seized with vomiting, vertigo, and ringing in his ears, and continued in an alarming condition for several days. During this time he heard tunes most distinctly played, and in accurate succession. This patient had, at the same time, a remarkable condition of vision, all objects appearing to him inverted. This peculiarity continued about three days, and ceased gradually; the objects by degrees changing their position, first to the horizontal, and then to the erect.

Some profess to have visions or sights relative to the world of spirits. This was the case with Swedenborg. He relates some of them in the following language: "I dined very late at my lodgings at London, and ate with great appetite, till, at the close of my repast, I perceived a kind of mist about my eyes, and the floor of my chamber was covered with hideous reptiles. They soon disappeared, the darkness was dissipated, and I saw clearly, in the midst of a brilliant light, a man seated in the corner of my chamber, who said to me, in a terrible voice, Eat not so much. At these words, my sight became obscured; afterwards it became clear by degrees, and I found myself alone. The night following, the same man, radiant with light, appeared to me, and said, I am God the Lord, Creator and Redeemer. I have chosen you to unfold to men the internal and spiritual sense of the sacred writings, and will dictate to you what you ought to write. At that time, I was not terrified, and the light, although very brilliant, made no unpleasant impression upon my eyes. The Lord was clothed in purple, and the vision lasted a quarter of an hour. The same night, the eyes of my internal man were opened, and fitted to see things in heaven, in the world of spirits, and in hell; in which places I have found many persons of my acquaintance, some of them long since dead, and others lately deceased." In another place, he observes, "I have conversed with apostles, departed popes, emperors, and kings; with the late reformers of the church, Luther, Calvin, and Melancthon, and with others from different countries." In conversing with Melancthon, he wished to know his state in the spirit world, but Melancthon did not see fit to inform him; "wherefore," says Swedenborg, "I was instructed by others concerning his lot, viz., that he is sometimes in an excavated stone chamber, and at other times in hell; and that when in the chamber, he appears to be clothed in a bear's skin by reason of the cold; and that on account of the filth in his chamber, he does not admit strangers from the world, who are desirous of visiting him from the reputation of his name."

The apparitions of Swedenborg were probably caused by his studies, habits, and pursuits. They bear the marks of earthly origin, although he firmly believed they were from heaven. Overloading his stomach at late meals, no doubt, caused some of them. He was in the habit of eating too much, as he himself admits. Hence his brain may have been disturbed. We have all heard of the case of an elderly lady, who, being ill, called upon her physician one day for advice. She told him, among other things, that on the preceding night her sleep had been disturbed—that she had seen her grandmother in her dreams. Being interrogated whether she ate any thing the preceding evening, she told the doctor she ate half a mince pie just before going to bed. "Well, madam," said he, "if you had eaten the other half, you might have seen your grandfather also."

The slightest examination of the accounts which remain of occurrences that were deemed supernatural by our ancestors will satisfy any one, at the present day, that they were brought about by causes entirely natural, although unknown to them. We will close this part of our investigation by relating the following circumstances, attested by the Rev. James Pierpont, pastor of a church in New Haven:—

"In the year 1647, a new ship of about one hundred and fifty tons, containing a valuable cargo, and several distinguished persons as passengers, put to sea from New Haven in the month of January, bound to England. The vessels that came over the ensuing spring brought no tidings of her arrival in the mother country. The pious colonists were earnest and instant in their prayers that intelligence might be received of the missing vessel. In the course of the following June, a great thunder storm arose out of the north-west; after which, (the hemisphere being serene,) about an hour before sunset, a ship of like dimensions of the aforesaid, with her canvas and colors abroad, (although the wind was northerly,) appeared in the air, coming up from the harbor's mouth, which lies southward from the town, seemingly with her sails filled, under a fresh gale, holding her course north, and continuing under observation, sailing against the wind, for the space of half an hour. The phantom ship was borne along, until, to the excited imaginations of the spectators, she seemed to have approached so near that they could throw a stone into her. Her main topmast then disappeared, then her mizzen topmast, then her masts were entirely carried away, and finally her hull fell off, and vanished from sight, leaving a dull and smoke-colored cloud, which soon dissolved, and the whole atmosphere became clear. All affirmed that the airy vision was a precise copy of the missing vessel, and that it was sent to announce and describe her fate. They considered it the spectre of the lost ship, and the Rev. Mr. Davenport declared in public 'that God had condescended, for the quieting of their afflicted spirits, this extraordinary account of his sovereign disposal of those for whom so many fervent prayers were made continually.'"

The results of modern science enable us to explain the mysterious appearance. It is probable that some Dutch vessel, proceeding slowly, quietly, and unconsciously on her voyage from Amsterdam to the New Netherlands, happened at the time to be passing through the Sound. At the moment the apparition was seen in the sky, she was so near, that her image was painted or delineated to the eyes of the observers, on the clouds, by the laws of optics, now generally well known, before her actual outlines could be discerned by them on the horizon. As the sun sunk behind the western hills, and his rays were gradually withdrawn, the visionary ship slowly disappeared, and the approach of the night, while it dispelled the vapors from the atmosphere, effectually concealed the vessel as she continued her course along the Sound.

The optical illusions that present themselves, on the sea shore, by which distant objects are raised to view, the opposite islands and capes made to loom up, lifted above the line of the apparent circumference of the earth, and thrown into every variety of shape which the imagination can conceive, are among the most beautiful phenomena of nature, and they impress the mind with the idea of enchantment and mystery, more perhaps than any others. But they have received a complete solution from modern discovery.

It should be observed that the optical principles that explain these phenomena have recently afforded a foundation for the science, or rather the art, of nauscopy. There are persons, it is said, in some places in the Isle of France, whose calling and profession it is to ascertain and predict the approach of vessels by their reflection in the atmosphere and on the clouds, long before they are visible to the eye or through the glass.

Our vision is at all times liable to be disturbed by atmospheric conditions. So long as the atmosphere between our person and the object we are looking at is of the same density, we may be said to see in a straight line to the object. But if, by any cause, a portion of that atmosphere is rendered less or more dense, the line of vision is bent, or refracted, from its course. A thorough comprehension of this truth in science has banished a mass of superstition. It has been found that, by means of powerful refraction, objects at great distances, and round the back of a hill, or considerably beneath the horizon, are brought into sight. In some countries this phenomenon is called mirage. The following is one of the most interesting and best-authenticated cases of the kind. In a voyage performed by Captain Scoresby, in 1822, he was able to recognize his father's ship, when below the horizon, from the inverted image of it which appeared in the air. "It was," says he, "so well defined, that I could distinguish, by a telescope, every sail, the general rig of the ship, and its particular character, insomuch that I confidently pronounced it to be my father's ship, the Fame,—which it afterwards proved to be—though on comparing notes with my father, I found that our relative position, at the time, gave our distance from one another very nearly thirty miles, being about seventeen miles beyond the horizon, and some leagues beyond the limit of direct vision!"

Dr. Vince, an English philosopher, was once looking through a telescope at a ship which was so far off that he could only see the upper part of the masts. The hull was entirely hidden by the bending of the water; but, between himself and the ship, he saw two perfect images of it in the air. These were of the same form and color as the real ship; but one of them was turned completely upside down.

In the sandy plains of Egypt, the mirage is seen to great advantage. These plains are often interrupted by small eminences, upon which the inhabitants have built their villages in order to escape the inundations of the Nile. In the morning and evening, objects are seen in their natural form and position; but when the surface of the sandy ground is heated by the sun, the land seems terminated, at a particular distance, by a general inundation; the villages which are beyond it appear like so many islands in a great lake; and an inverted image of a village appears between the hills.

The Swedish sailors long searched for a supposed magic island, which, from time to time, could be descried between the Island of Aland and the coast of Upland. It proved to be a rock, the image of which was presented in the air by mirage. At one time, the English saw, with terror, the coast of Calais and Boulogne, in France, rising up on the opposite side of the Channel, and apparently approaching their island. But the most celebrated example of mirage is exhibited in the Straits of Messina. The inhabitants of the Calabrian shore behold images of palaces, embattled ramparts, houses, and ships, and all the varied objects of towns and landscapes, in the air—being refracted images from the Sicilian coast. This wonderful phenomenon is superstitiously regarded by the common people as the work of fairies.