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original genius; and the method of analysis gives us no satisfaction with respect to the process by which they are obtained.

To remove this difficulty completely, by explaining all the various ways in which new theorems may be brought to light, would lead to inquiries foreign to this work. In order, however, to render the process of the mind, on such occasions, a little less mysterious than it is commonly supposed to be, it may be proper to remark, that the most copious source of discoveries is the investigation of problems, which seldom fails (even although we should not succeed in the attainment of the object which we have in view) to exhibit to us some relations formerly unobserved among the quantities which are under consideration. Of so great importance is it to concentrate the attention to a particular subject, and to check that wandering and dissipated habit of thought, which, in the case of most persons, renders their speculations barren of any profit either to themselves or to others. Many theorems, too, have been suggested by analogy; many have been investigated from truths formerly known by altering or by generalizing the hypothesis ; and many have been obtained by a species of induction. An illustration of these various processes of the mind would not only lead to new and curious remarks, but would contribute to diminish that blind admiration of original genius, which is one of the chief obstacles to the improvement of science.

The history of natural philosophy, before and after the time of Lord Bacon, affords another proof how much the powers of invention and discovery may be assisted by the study of method; and in all the sciences, without exception, whoever employs his genius with a regular and habitual success, plainly shews that it is by means of general rules that his inquiries are conducted. Of these rules, there may be many which the inventor never stated to himself in words, and, perhaps, he may even be unconscious of the assistance which he derives from them; but their influence on his genius appears unquestionably from the uniformity with which it proceeds, and in proportion as they can be ascertained by his own speculations, or collected by the logician from an examination of his researches, similar powers

of invention will be placed within the reach of other men, who apply themselves to the same study.

The following remarks, which a truly philosophical artist has applied to painting, may be extended, with some trifling alterations, to all the different employments of our intellectual powers.

“ What we now call genius begins, not where rules, abstractedly taken, end, but where known, vulgar and trite rules have no longer any place. It must of necessity be, that works of genius, as well as every other effect, as it must have its cause, must likewise have its rules; it cannot be by chance that excellencies are produced with any constancy, or any certainty, for this is not the nature of chance; but the rules by which men of extraordinary parts, and such as are called men of genius, work, are either such as they discover by their own peculiar observation, or of such a nice texture as not easily to admit handling or expressing in words.

“ Unsubstantial, however, as these rules may seem, and difficult as it may be to convey them in writing, they are still seen and felt in the mind of the artist, and he works from them with as much certainty, as if they were embodied, as I may say, upon paper. It is true, these refined principles cannot be always made palpable, like the more gross rules of art; yet it does not follow, but that the mind may be put in such a train, that it shall perceive, by a kind of scientific sense, that propriety which words can but very feebly suggest."

SECT. V. - APPLICATION OF THE PRINCIPLES STATED IN THE

FOREGOING SECTIONS OF THIS CHAPTER, TO EXPLAIN THE PHENOMENA OF DREAMING.

With respect to the Phenomena of Dreaming, three different questions may be proposed. First, What is the state of the mind in sleep? or, in other words, what faculties then continue to operate, and what faculties are then suspended ? Secondly, How far do our dreams appear to be influenced by our bodily

1 Discourses, by Sir Joshua Reynolds.

VOL. II.

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sensations; and in what respects do they vary, according to the different conditions of the body in health and in sickness? Thirdly, What is the change which sleep produces on those parts of the body with which our mental operations are more immediately connected; and how does this change operate, in diversifying so remarkably the phenomena which our minds then exhibit, from those of which we are conscious in our waking hours ? Of these three questions, the first belongs to the Philosophy of the Human Mind; and it is to this question that the following inquiry is almost entirely confined. The second is more particularly interesting to the medical inquirer, and does not properly fall under the plan of this work. The third seems to me to relate to a subject which is placed beyond the reach of the human faculties.

It will be granted that, if we could ascertain the state of the mind in sleep, so as to be able to resolve the various phenomena of dreaming into a smaller number of general principles ; and still more, if we could resolve them into one general fact; we should be advanced a very important step in our inquiries upon this subject, even although we should find it impossible to shew in what manner this change in the state of the mind results from the change which sleep produces in the state of the body. Such a step would at least gratify, to a certain extent, that disposition of our nature which prompts us to ascend from particular facts to general laws, and which is the foundation of all our philosophical researches; and, in the present instance, I am inclined to think that it carries us as far as our imperfect faculties enable us to proceed.

In conducting this inquiry with respect to the state of the mind in sleep, it seems reasonable to expect that some light may be obtained from an examination of the circumstances which accelerate or retard its approach ; for when we are disposed to rest, it is natural to imagine that the state of the mind approaches to its state in sleep more nearly than when we feel ourselves alive and active, and capable of applying all our various faculties to their proper purposes.

In general, it may be remarked that the approach of sleep is

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accelerated by every circumstance which diminishes or suspends the exercise of the mental powers; and is retarded by everything which has a contrary tendency. When we wish for sleep, we naturally endeavour to withhold, as much as possible, all the active exertions of the mind, by disengaging our attention from every interesting subject of thought. When we are disposed to keep awake, we naturally fix our attention on some subject which is calculated to afford employment to our intellectual powers, or to rouse and exercise the active principles of our nature.

It is well known that there is a particular class of sounds which compose us to sleep. The hum of bees, the murmur of a fountain, the reading of an uninteresting discourse, have this tendency in a remarkable degree. If we examine this class of sounds, we shall find that it consists wholly of such as are fitted to withdraw the attention of the mind from its own thoughts, and are, at the same time, not sufficiently interesting to engage its attention to themselves.1

It is also matter of common observation, that children and persons of little reflection, who are chiefly occupied about sensible objects, and whose mental activity is, in a great measure, suspended as soon as their perceptive powers are unemployed, find it extremely difficult to continue awake when they are deprived of their usual engagements. The same thing has been remarked of savages, whose time, like that of the lower animals, is almost completely divided between sleep and their bodily exertions.?

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(Lord Bacon has taken notice of this moveth attention, withont too much fact; and the account he has given of labour, stilleth the natural and discurit (so far as relates to the power of sive motion of the spirits.") attention) is not very wide of the truth. His theory concerning "the Motion of 3 "The existence of the Negro slaves the Spirits" furnishes a proof of the in America appears to participate more proneness of those men who are the of sensation than reflection. To this most fully aware of the importance of must be ascribed their disposition to experiment and observation in physics, sleep when abstracted from their diverto indulge in hypotheses in explaining sions, and unemployed in their labour. the phenomena of the human mind. An animal whose body is at rest, and " Some noises help sleep, as the blowing who does not reflect, must be disposed of wind, and the trickling of water; they to sleep of course."--Notes on Virginia, move a gentle attention, and whatsoever by Mr. Jefferson, p. 255.

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From a consideration of these facts, it seems reasonable to conclude, that in sleep those operations of the mind are suspended which depend on our volition ; for if it be certain, that before we fall asleep we must withhold, as much as we are able, the exercise of all our different powers, it is scarcely to be imagined that, as soon as sleep commences, these powers should again begin to be exerted. The more probable conclusion is, that when we are desirous to procure sleep, we bring both mind and body, as nearly as we can, into that state in which they are to continue after sleep commences. The difference, therefore, between the state of the mind when we are inviting sleep, and when we are actually asleep, is this, that in the former case, although its active exertions be suspended, we can renew them if we please. In the other case, the will loses its influence over all our powers both of mind and body, in consequence of some physical alteration in the system, which we shall never, probably, be able to explain.

In order to illustrate this conclusion a little farther, it may be proper to remark, that if the suspension of our voluntary operations in sleep be admitted as a fact, there are only two suppositions which can be formed concerning its cause. The one is, that the power of volition is suspended; the other, that the will loses its influence over those faculties of the mind and those members of the body which, during our waking hours, are subjected to its authority. If it can be shewn, then, that the former supposition is not agreeable to fact, the truth of the latter seems to follow as a necessary consequence.

1. That the power of volition is not suspended during sleep, appears from the efforts which we are conscious of making while in that situation. We dream, for example, that we are in danger, and we attempt to call out for assistance. The attempt, indeed, is in general unsuccessful, and the sounds which we emit are feeble and indistinct, but this only confirms, or rather, is a necessary consequence of the supposition, that in sleep the connexion between the will and our voluntary operations is disturbed or interrupted. The continuance of the power of volition is demonstrated by the effort, however ineffectual.

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