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far as it depends on the laws of association, may be carried on by the operation of the same unknown causes by which it is produced while we are awake; and, Secondly, that the order of our thoughts, in these two states of the mind, must be very different; inasmuch as, in the one, it depends solely on the laws of association, and in the other, on these laws combined with our own voluntary exertions.
In order to ascertain how far these conclusions are agreeable to truth, it is necessary to compare them with the known phenomena of dreaming. For which purpose, I shall endeavor to show, first, that the succession of our thoughts in sleep, is regulated by the same general laws of association, to which it is subjected while we are awake; and, secondly, that the circumstances which discriminate dreaming from our waking thoughts, are such as must necessarily arise from the suspension of the influence of the will.
I. That the succession of our thoughts in sleep, is regulated by the same general laws of association, which influence the mind while we are awake, appears from the following considerations.
1. Our dreams are frequently suggested to us by bodily sensations; and with these it is well known, from what we experience while awake, that particular ideas are frequently very strongly associated. I have been told by a friend, that having occasion, in consequence of an indisposition, to apply a bottle of hot water to his feet when he went to bed, he dreamed that he was making a journey to the top of Mount Ætna, and that he found the heat of the ground almost insupportable. Another person, having a blister applied to his head, dreamed that he was scalped by a party of Indians. I believe every one who is in the habit of dreaming, will recollect instances, in his own case, of a similar nature.
2. Our dreams are influenced by the prevailing temper of the mind; and vary, in their complexion, according as our habitual disposition, at the time, inclines us to cheerfulness or to melancholy. Not that this observation holds without exception; but it holds so generally, as must convince us, that the state of our spirits has some effect on our dreams, as well as on our waking thoughts. Indeed, in the latter case, no less than in the former, this effect may be counteracted, or modified by various other circumstances.
After having made a narrow escape from any alarming danger, we are apt to awake, in the course of our sleep, with sudden startings; imagining that we are drowning, or on the brink of a precipice. A severe misfortune, which has affected the mind deeply, influences our dreams in a similar way; and suggests to us a variety of adventures, analogous, in some measure, to that event from which our distress arises. Such, according to Virgil, were the dreams of the forsaken Dido.
-Agit ipse furentem,
3. Our dreams are influenced by our prevailing habits of association while awake.
In a former part of this work, I considered the extent of that power which the mind may acquire over the train of its thoughts ; and I observed, that those intellectual diversities among men, which we commonly refer to peculiarities of genius, are, at least in a great measure, resolvable into differences in their habits of association. One man possesses a rich and beautiful fancy, which is at all times obedient to his will. Another possesses a quickness of recollection, which enables him, at a moment's warning, to bring together all the results of his past experience, and of his past reflections, which can be of use for illustrating any proposed subject. A third can, without effort, collect his attention to the most abstract questions in philosophy; can perceive, at a glance, the shortest and the most effectual process for arriving at the truth; and can banish from his mind every extraneous idea, which fancy or casual association may suggest, to distract his thoughts, or to mislead his judgment. A fourth unites all these powers in a capactity of perceiving truth with an almost intuitive rapidity; and in an eloquence which enables him to command, at pleasure, whatever his memory and his fancy can supply, to illustrate and to adorn it. The occasional exercise which such men make of their powers, may undoubtedly be said, in one sense, to be unpremeditated or unstudied; but they all indicate previous habits of meditation or study, as unquestionably, as the dexterity of the expert accountant, or the rapid execution of the professional musician.
From what has been said, it is evident, that a train of thought which, in one man, would require a painful effort of study, may, in another, be almost spontaneous: nor is it to be doubted, that the reveries of studious men, even when they allow as much as they can, their thoughts to follow their own course, are more or less connected together by those principles of association, which their favorite pursuits tend more particularly to strengthen.
The influence of the same habits may be traced distinctly in sleep. There are probably few mathematicians, who have not dreamed of an interesting problem, and who have not even fancied that they were prosecuting the investigation of it with much success. They whose ambition leads them to the study of eloquence, are frequently conscious, during sleep, of a renewal of their daily occupations ; and sometimes feel themselves possessed of a fluency of speech, which they never experienced before. The poet, in his dreams, is transported into Elysium, and leaves the vulgar and unsatisfactory enjoyments of humanity, to dwell in those regions of enchantment and rapture, which have been created by the divine imaginations of Virgil and of Tasso.
“ And hither Morpheus sent his kindest dreams,
Raising a world of gayer tinct and grace;
That play'd, in waving lights, from place to place,
Ne could it e'er such melting forms display,
No, fair illusions ! artful phantoms, no!
As a farther proof that the succession of our thoughts in dreaming, is influenced by our prevailing habits of association; it may be remarked, that the scenes and occurrences which most frequently present themselves to the mind while we are asleep, are the scenes and occurrences of childhood and early youth. The facility of association is then much greater than in more advanced years; and although, during the day, the memory of the events thus associated, may be banished by the objects and pursuits which press upon our senses, it retains a more permanent hold of the mind than any of our subsequent acquisitions: and like the knowledge which we possess of our mother tongue, is, as it were, interwoven and incorporated with all its most essential habits. Accordingly, in old men, whose thoughts are, in a great measure, disengaged from the world, the transactions of their middle age, which once seemed so important, are often obliterated; while the mind dwells, as in a dream, on the sports and the companions of their infancy.
I shall only observe farther, on this head, that in our dreams, as well as when awake, we occasionally make use of words as an instrument of thought. Such dreams, however, do not affect the mind with such emotions of pleasure and of pain, as those in which the imagination is occupied with particular objects of sense. The effect of philosophical studies, in habituating the mind to the almost constant employment of this instrument, and, of consequence, its effect in weakening the imagination, was formerly remarked. If I am not mistaken, the influence of these circumstances may also be traced in the history of our dreams; which, in youth commonly involve, in a much greater degree, the exercise of imagination ; and affect the mind with much more powerful emotions, than when we begin to employ our maturer faculties in more general and abstract speculations.
Il. From these different observations, we are authorized to conclude, that the same laws of association which regulate the train of our thoughts while we are awake, continue to operate during sleep. I now proceed to consider, how far the circumstances which discriminate dreaming from our waking thoughts correspond with those which might be expected to result from the suspension of the influence of the will.
1. If the influence of the will be suspended during sleep, all our voluntary operations, such as recollection, reasoning, &c. must also be suspended.
That this really is the case, the extravagance and inconsistency of our dreams are sufficient proofs. We frequently confound together times and places the most remote from each other; and in the course of the same dream, conceive the same person as existing in different parts of the world. Sometimes we imagine ourselves conversing with a dead friend, without remembering the circumstance of his death, although, perhaps, it happened but a few days before, and affected us deeply. All this proves clearly, that the subjects which then occupy our thoughts are such as present themselves to the mind spontaneously; and that we have no power of employing our reason in comparing together the different parts of our dreams; or even of exerting an act of recollection in order to ascertain how far they are consistent and possible.
The process of reasoning in which we sometimes fancy ourselves to be engaged during sleep, furnish no exception to the foregoing observation; for, although every such process, the first time we form it, implies volition ; and, in particular, implies a recollection of the premises, till we arrive at the conclusion ; yet, when a number of truths have been often presented to us as necessarily connected with each other, this series may afterwards pass through the mind, according to the laws of association, without any more activity on our part, than in those trains of thought which are the most loose and incoherent. Nor is this mere theory. I may venture to appeal to the consciousness of every man accustomed to dream, whether his reasonings during sleep do not seem to be carried on without any exertion of his will ; and with a degree of facility of which he was never conscious while awake. Mr. Addison, in one of his Spectators, has made this observation ; and his testimony, in the present instance, is of the greater weight, that he had no particular theory on the subject to support. " There is not,” says he, “a more painful action of the mind than invention, yet in dreams it works with that ease and activity, that we are not sensible when the faculty is employed. For instance, I believe every one, some time or other, dreams that he is reading papers, books, or letters; in which case the invention prompts so readily that the mind is imposed on, and mistakes its own suggestions for the composition of another.” (No. 487.)
2. If the influence of the will during sleep be suspended, the mind will remain as passive, while its thoughts change from one subject to another, as it does during our waking hours, while different perceptible objects are presented to our senses.
Of this passive state of the mind in our dreams it is unnecessary to multiply proofs ; as it has always been considered as one of the most extraordinary circumstances with which they are accompanied. If our dreams, as well as our waking thoughts, were subject to the will, is it not natural to conclude, that in the one case, as well as in the other, we would endeavor to banish, as much as we could, every idea which had a tendency to disturb us; and detain
those only which we found to be agreeable ? So far, however, is this power over our thoughts from being exercised, that we are frequently oppressed, in spite of all our efforts to the contrary, with dreams which affect us with the most painful emotions. And, indeed, it is matter of vulgar remark, that our dreams are, in every case, involuntary on our part; and that they appear to be obtruded on us by some external cause. This fact appeared so unaccountable to the late Mr. Baxter, that it gave rise to his very whimsical theory, in which he ascribes dreams to the immediate influence of separate spirits on the mind.
3. If the influence of the will be suspended during sleep, the conceptions which we then form of sensible objects will be attended with a belief of their real existence, as much as the perception of the same objects is while we are awake.
In treating of the power of conception, I formerly observed, that our belief of the separate and independent existence of the objects of our perceptions, is the result of experience; which teaches us that these perceptions do not depend on our will. If I open my eyes, I cannot prevent myself from seeing the prospect before me. The case is different with respect to our conceptions. While they occupy the mind, to the exclusion of every thing else, I endeavored to show, that they are always accompanied with belief: but as we can banish them froin the mind, during our waking hours, at pleasure; and as the momentary belief which they produce, is contin-, ually checked by the surrounding objects of our perceptions, we learn to consider them as fictions of our own creation ; and, excepting in some accidental cases, pay no regard to them in the conduct of life. If the doctrine however formerly stated with respect to conception be just, and if, at the same time it be allowed, that sleep suspends the influence of the will over the train of our thoughts, we should naturally be led to expect, that the same belief which accompanies conception wbile we are awake, should accompany the perceptions which occur to us in our dreams. It is scarcely necessary for me to remark, how strikingly this conclusion coincides with acknowledged facts.
May it not be considered as some confirmation of the foregoing doctrine, that when opium fails in producing complete sleep, it commonly produces one of the effects of sleep, by suspending the activity of the mind, and throwing it into a reverie ; and that while we are in this state, our conceptions frequently affect us nearly in the same manner, as if the objects conceived were present to our senses ?—(See the Baron de Totts's Account of the Opium-takers at Constantinople.)
Another circumstance with respect to our conceptions during sleep, deserves our notice. As the subjects which we then think upon occupy the mind exclusively; and as the attention is not diverted by the objects of our external senses, our conceptions must be proportionably lively and steady. Every person knows how