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a shadow never falls upon a wall without leaving thereupon its permanent trace-a trace which might be made visible by resorting to proper processes. But if on such inorganicé surfaces impressions may in this way be preserved, how much more likely is it that the same thing occurs in the purposely constituted ganglia6 of the brain !” But, whether the impressions of sense be permanently fixed in the material substance of the brain or not, there is no reason for supposing that any perceptions which the mind has once taken notice of can ever be lost; and if at any time memory fails to recall them, it is because the brain, and not the mind itself, has become im

paired.

6. While, in the exercise of ordinary memory, perceptions and trains of thought are recalled in their real character and natural order, it is not so in what are called visions, fancied apparitions, and in dreams. The most common visions—unreal objects which we fancy-are doubtless the remains of impressions which have been made on the optic? nerve, and which are recalled by a strong mental effort. Others arise from disease of the nerve, often producing, by the impressions conveyed from the diseased nerve to the brain, grotesque images among the real objects at which we are looking. Some unusual pressure of blood upon this nerve will often produce apparent flashes of light, or objects apparently floating in the air. These appearances are indications of disease in the nerve.

7. When, in addition to the optic nerve, portions of the brain become affected by disease, former impressions often become mingled with the present, and the complicated scenes of a passing drama are displayed. Thus, in the delirium tremens, which follows a cessation from the customary use of alcohol, phantoms appear moving around among real objects. “ The form of a cloud no bigger than the hand may perhaps first be seen floating over the carpet; but this, as the eye follows it, takes on a sharp contours and definite shape, and the sufferer sees with dismay a moping raven on some of the more distant articles of furniture. Or, out of an indistinct cloud, faces, sometimes of surprising loveliness, but more frequently of hideous aspects, emerge, one face succeeding as another dies away. The mind, ever ready to practice imposture upon itself, will at last accompany the illusion with grotesque or even dreadful inventions."

8. The illusions to which one is subject under such derangements of the brain take a character from the previous occupations, travel, mental habits, or reading of the sick man. " Former trains of thought, and former scenes, although often confusedly mingled, assume, to the individual himself, all the vividness of existing realities. “I saw,” says De Quincey in his Confessions of an Opium Eater, “as I lay awake in bed, vast processions, that passed along in mournful pomp; friezes of never-ending stories, 10 that to my feelings were as sad and solemn as if they were stories drawn from times before Edipus or Priam, before Tyre, before Memphis; and, at the same time, a corresponding change took place in my dreams; a theatre seemed suddenly opened and lighted up within my brain, which presented nightly spectacles of more than earthly splendor.”

9. What are called “ apparitions,” or spectral appearances, physiology explains upon satisfactory scientific principles. They arise sometimes from a disturbance of the retinali alone, which gives a false interpretation of present impressions, sometimes from the vivid recalling of old images which have been stored up in the brain, but which the mind then looks upon as present realities, and sometimes the two causes unite to produce the effect. Upon these principles, the mind, in apparitions, could never see any thing absolutely new to it. And such are the facts. Thus the Greeks and the Romans were just as liable to disorders of the nervous system as we are; but to them supernatural appearances came under the mythological forms of their heathen divinities. The ascetics12 of the Middle Ages saw phantoms of the Virgin and the saints, for these were the objects which their minds most dwelt upon; and at a later period, in Northern Europe, fairies, brownies, and Robin Goodfellows were the phantoms most frequently seen. In the Middle Ages, spectres of African negroes were common enough; but at that period no-man had ever witnessed one of an American Indian, yet these, in their turn, prevailed after the voyage of Columbus. They were no strangers to our early colonial settlers.

10. One class of apparitions—those of the dead-has survived all changes of creed and superstitions, as we might reasonably suppose would be the case. But even here, as the phenomena consist merely of the emergence of old images, and new combinations of them, nothing absolutely new was ever seen in them. The Roman saw the shade of his friend clothed in the well-known toga:13 the European sees his in the modern garb; and the spirit of Maupertuis, 14 which stood by the bay-window of the library at Berlin, had on knee-breeches, silk stockings, and shoes with large silver buckles. If these

apparitions existed elsewhere than in a diseased brain, is it not singular that, amid the awful solemnities of the other world, they should so faithfülly have preserved the fashions of the present ? Science is a great dispeller of superstitious fancies.

1 IN-VÖL'-UN-TA-BY, independent of the will. 10 STO'-RIES, lofts, or sets of rooms rising one 2 E-RĂD'-I-CĀ-TED, rooted out; destroyed. above another." 3 SPĚC'-TRAL, having an indistinct or ghostly 11 RĚT'-I-NA, the net-like membrane at the appearance.

back of the eye which receives the image 4 DE-TĒ'-RI-O-RĀTE, impair; injure.

of external objects. See p. 83. S IN-OR-GĂN'Ie, without the organs or instru- 12 As-CĒT'-I€, one who practices undue rigor ments of life.

or self-denial in religious things. 6 GĂNG-LI-Ä, nerve bundles.

13 TO'-GA, a kind of gown. 7 Op'-TIC NERVE, the nerve of vision, run- 14 MAU-PER-TUIS' (Mo-per-twe'), a celebrated ning from' the eye to the brain.

French academician-born in 1698_died 8 CON-TÖUE, outline of a thing.

in 1759. For a long time he was president 9 FRIĒZE, in architecture, a part of the en- of the Royal Academy of Sciences at Ber

tablature. See p. 282.

lin.

LESSON XVII.-A DREAM, AND ITS EXPLANATION.

DRAPER. 1. Not only may old impressions and ideas be so vividly recalled as to be presented to the mind with all the force of existing realities, but in this manner dreams are sometimes repeated ; and although there is nothing strange in this, but what we should suppose would happen frequently, yet the ignorant often regard such phenomena as something bordering on the supernatural. For the following account, given by a physician, of one of the most marvelous dreams of this character, and its explanation on physiological principles, we are indebted to the work of Dr. Draper.

2. “When I was five or six years old,” says the narrator, “I dreamed that I was passing by a large pond of water in a solitary place. On the opposite side of it stood a great tree, that looked as if it had been struck by lightning; and in the pond, at another part, an old fallen trunk, on one of the prone limbs of which was a turtle sunning himself. On a sudden a wind arose, which forced me into the pond; and in my dying struggles to extricate myself from its green and slimy waters I awoke, trembling with terror.

3. “ About eight years subsequently, while recovering from a nearly fatal attack of scarlet fever, this dream presented itself to me again, identical in all its parts. Even up to this time I do not think I had ever seen a living tortoise or turtle, but I indistinctly remembered there was a picture of one in the first spelling-book that had been given me. Perhaps, on account of my critical condition, this second dream impressed me more dreadfully than the first.

4. “A dozen years more elapsed. I had become a physician, and was now actively pursuing my professional duties in one of the Southern States. It so fell out that one July afternoon I had to take a long and wearisome ride on horseback. It was Sunday, and extremely hot; the path was soli.

tary, and not a house for miles. The forest had that intense silence which is so characteristic of this part of the day; all the wild animals and birds seemed to have gone to their retreats, to be rid of the heat of the sun. Suddenly, at one point of the road, I came upon a great stagnant water-pool, and, casting my eye across it, there stood a pine-tree blasted by lightning, and on a log that was nearly even with the surface a turtle was basking in the sun. The dream of my infancy was upon me; the bridle fell from my hands; and an unutterable fear overshadowed me as I slunk away from the accursed place.

5. "Though business occasionally afterward would have drawn me that way, I could not summon the resolution to go, and actually have taken roundabout paths. It seemed to me profoundly amazing that the dream which I had twenty years before should now be realized, without respect to difference of scenery, or climate, or age. A good clergyman of my acquaintance took the opportunity of improving the circumstance to my spiritual advantage; and in his kind enthusiasm, for he knew that I had, more than once, been brought to the point of death by such fevers, interpreted my dream that I should die of marsh miasm.3

6. "Most persons have doubtless observed that they suddenly encounter circumstances or events of a trivial nature in their course of life, of which they have an indistinct recollection that they have dreamed before. It seemed for a long time to me that this was a case of that kind, and that it might he set down among the mysterious and unaccountable. How wonderful it is that we so often fail to see the simple explanation of things, when that explanation is actually intruding itself before us.

7. “And so in this case; it was long before the truth gleamed in upon me, before my reasoning powers shook off the delusive impressions of my senses. But it occurred at last, for I said to myself, “Is it more probable that such a mystery is true', or that I have dreamed for the third time that which I had already dreamed of twice before'? Have I really seen the blasted tree and the sunning turtle' ? Are a weary ride of fifty miles, the noontide heat, the silence that could almost be felt, no provocatives4 of a dream'? I have ridden, under such circumstances, many a mile, fast asleep, and have awoke and known it-and so I resolved that if ever circumstances carried me to those parts again, I would satisfy myself as to the matter.

8. “Accordingly,when, after a few years, an incident led me to travel there, I revisited the well-remembered scene. There still was the stagnant pool, but the blasted pine-tree was gone; and, after I had pushed my horse through the marshy thicket as far as I could urge him, and then dismounted and pursued a close investigation on foot in every direction round the spot, I was clearly convinced that no pine-tree had ever grown there; not a stump, nor · any token of its remains, could be seen; and so now I have concluded that, at the glimpse of the water, with the readiness of those who are falling asleep I had adopted an external fact into a dream ; that it had aroused the trains of thought which, in former years, had occupied me; and that, in fine, the mystery was all a delusion, and that I had been frightened with less than a shadow.”

9. The instructive story of this physician teaches us how readily, and yet how impressively, the remains of old ideas may be recalled; how they may, as it were, be projected5 into the space beyond us, and take a position among existing re

alities. That such images arise from a physical impression which has formerly been made in the registering ganglia of the brain, it is impossible to doubt; and it is philosophical to suppose that, for their emergence from their dormant? state, it is only necessary that there should be a dulling or blunting of the sensations which we are in the act of receiving from external sources, so that these latent8 relics, laid up in the brain, may present themselves with at least equal force. 1 SU-PER-NĂT'-U-RAL, above or beyond the 5 PRO-JEET'-ED, thrust forward. laws of nature; miraculous.

6 E-MÈR'-GENCE, a coming forth. 2 PBONE, bending down ward. 3 Mi'-Asm, noxious vapors or effluvia. '8 LA'-TENT, not visible; concealed. 1 PRO-VO'-CA-TIVE, that which excites or leads to.

forth.

s POR MANT, sleeping

19.vo'-CA-TÏVE. thot or effluvia

LESSON XVIII.—THE HEALTH OF THE BRAIN. 1. ALTHOUGH the brain is the seat of thought, of feeling, and of consciousness, it is nevertheless a part of the animal system. Do not make a mistake in supposing that the brain is the mind itself. It is merely the organ of the mind—the medium through which the mind acts. In like manner, speech is not thought itself; it is merely an instrument by which thought is conveyed from one mind to another.

2. The brain is subject to the same general laws of health as the other bodily organs; and, like them, it is liable to disease. It is nourished by the blood; it is strengthened by mental exercise; it is injured by over-exertion; and it is enfeebled by disease. When the mind thinks intently, an increased quantity of blood is sent to the brain to supply the waste of material occasioned by exercise of that organ. The brain is then enlarged in bulk; and hence we see the danger of too long continued intense application, which often results in congestion of the brain, apoplexy,” and death. So, also, if the brain be highly excited by the excessive use of stimulants, a rush of blood to the brain will be the consequence, and the mind will be disturbed; and if, on the other hand, the mind be suddenly roused by violent passions, the vessels of the brain will instantly be excited to increased action, redness will suffuse the face, and the disturbance will be the same as if produced by a physical cause.

3. Although the weight of the brain is only about one fortieth of the weight of the body, yet ordinarily about one sixth of all the blood is sent to this organ. If more than the usual quantity be sent there, as will happen in cases of intense and

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