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DUGALD STEWART,

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III. DUGALD STEWART.

DUGALD STEWART was born at Edinburgh in 1753, and, after the usual education at the High School and University of his native town, became Professor of Mathematics in the University. In 1785 he was removed to the more congenial position of Professor of Moral Philosophy, and his reputation as a lecturer added much to the lustre of the university, and attracted auditors from all parts of the kingdom. Parts of his lectures were in 1792 published as the first volume of the Elements of the Philosophy of the Human Mind;" and the work was completed by the appearance of a second volume in 1814 and a third in 1827. They were received with more public favour than usually accompanies works of a metaphysical kind, and the same patronage was extended to his "Outlines of Moral Philosophy," a brief compend of the views insisted upon in his lectures, and intended as a text-book for students. The growing infirmities of age compelled him to resign his chair to his well-known successor, Dr Thomas Brown; and, after some years of retirement, he died in 1828. Besides the works enumerated, he wrote the "Preliminary Dissertation on Mental Philosophy," in the “ Encyclopædia Britannica," Philosophical Essays," and "Memoirs of Smith, Reid, and Robertson." Stewart, though not a very profound speculator, possessed extensive learning, good taste, sound judgment, and considerable acuteness; and these accomplishments, added to the graces of a clear and elegant style, give him a high rank among philosophical writers. The following extracts are made from the last edition of Stewart's works, that of Sir William Hamilton, which differs in some particulars from any preceding edition:

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1. STATE OF THE MIND DURING SLEEP.

In conducting the 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 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. It is also a 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.

From a consideration of these facts, it seems reasonable to conclude, that in sleep these 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 shown, 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 connection 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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In like manner, in the course of an alarming dream, we are sometimes conscious of making an exertion to save ourselves by flight from an apprehended danger; but in spite of all our efforts we continue in bed. In such cases we commonly dream that we are attempting to escape, and are prevented by some external obstacle, but the fact seems to be that the body is at that time not subject to the will. During the disturbed rest which we sometimes have when the body is indisposed, the mind appears to retain some power over it; but as, even in these cases, the motions which are inade consist rather of a general agitation of the whole system, than of the regular exertion of a particular member of it with a view to produce a certain effect, it is reasonable to conclude that in perfectly sound sleep, the mind, although it retains the power of volition, retains no influence whatever over the bodily organs.

In that particular condition of the system which is known by the name of incubus, we are conscious of a total want of power over the body; and I believe the common opinion is, that it is the want of power which distinguishes the incubus from all the other modifications of sleep. But the more probable supposition seems to be, that every species of sleep is accompanied with a suspension of the faculty of voluntary motion; and that the incubus has nothing peculiar in it but this, that the uneasy sensations which are produced by the accidental posture of the body, and which we find it impossible to remove by our own efforts, renders us distinctly conscious of our incapacity to move. One thing is certain, that the instant of our awaking, and of our recovering the command of our bodily organs, is one and the same.

2. The same conclusion is confirmed by a different view of the subject. It is probable, as was already observed, that when we are anxious to procure sleep, the state into which we naturally bring the mind approaches to its state after sleep commences. Now, it is manifest that the means which nature directs us to employ on such occasions is not to suspend the power of volition, but to suspend the exertion of those powers whose exercise depends on volition. If it were necessary that volition should be suspended before we fall asleep, it would be impossible for us by our own efforts to hasten the moment of rest. The very supposition of such efforts is absurd, for it implies a continued will to suspend the acts of the will.

According to the foregoing doctrine, with respect to the state of the mind in sleep, the effect which is produced on our mental operations is strikingly analagous to that which is produced on our bodily powers. From the observations which have been already made, it is manifest that in sleep the body is in a very inconsiderable degree, if at all, subject to our command. The vital and involuntary motions, however, suffer no interruption, but go on as when we are awake, in consequence of the operation of some cause unknown to us. In like manner, it would appear that those operations of the mind which depend on our volition are suspended, while certain other operations are at least occasionally carried on.

This analogy naturally suggests the idea, that all our mental operations which are independent of our will may continue during sleep, and that the phenomena of dreaming may perhaps be produced by these, diversified in their apparent effects, in consequence of the suspension of our voluntary powers.

2. THE VARIETIES OF MEMORY IN DIFFERENT INDIVIDUALS.

It is generally supposed, that of all our faculties, memory is that which nature has bestowed in the most unequal degrees on different individuals; and it is far from being impossible that this opinion may be well founded. If, however, we consider that there is scarcely any man who has not memory sufficient to learn the use of language, and to learn to recognise, at the first glance, the appearances of an infinite number of familiar objects; besides acquiring such an acquaintance with the laws of nature, and the ordinary course of human affairs, as is necessary for directing his conduct in life, we shall be satisfied that the original disparities among men, in this respect, are by no means so immense as they seem to be at first view; and that much is to be ascribed to different habits of attention, and to a difference of selection among the various events presented to their curiosity.

It is worthy of remark, also, that those individuals who possess unusual powers of memory with respect to any one class of objects, are commonly as remarkably deficient in some of the other applications of that faculty. I knew a person who, though completely ignorant of Latin, was able to repeat over thirty or forty lines of Virgil, after having heard them once read to him,-not, indeed, with perfect exactness, but with such a degree of resemblance as (all circumstances considered) was truly astonishing; yet this person (who was in the condition of a servant) was singularly deficient in memory in all cases in which that faculty is of real practical utility. He was noted in every family in which he had been employed for habits of forgetfulness, and could scarcely deliver an ordinary message without committing some blunder.

A similar observation, I can almost venture to say, will be found to apply to by far the greater number of those in whom this faculty seems to exhibit a preternatural or anomalous degree of force. The varieties of memory are indeed wonderful, but they ought not to be confounded with inequalities of memory. One man is distinguished by a power of recollecting names, and dates, and genealogies; a second, by the multiplicity of speculations, and of general conclusions treasured up in his intellect; a third, by the facility with which words and combinations of words (the very words of a speaker or of an author) seems to lay hold of his mind; a fourth, by the quickness with which he seizes and appropriates the sense and meaning of an author, while the phraseology and style seem altogether to escape his notice; a fifth, by his memory for poetry; a sixth, by his memory for music; a seventh, by his memory for architecture,

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statuary, and painting, and all the other objects of taste which are addressed to the eye. All these different powers seem miraculous to those who do not possess them; and as they are apt to be supposed by superficial observers to be commonly united in the same individuals, they contribute much to encourage those exaggerated estimates concerning the original inequalities among men in respect to this faculty which I am now endeavouring to reduce to their first standard.

As the great purpose to which this faculty is subservient is to enable us to collect and to retain, for the future regulation of our conduct, the results of our past experience, it is evident that the degree of perfection which it attains in the case of different persons must vary; first, with the facility of making the original acquisition; secondly, with the permanence of the acquisition; and thirdly, with the quickness or readiness with which the individual is able, on particular occasions, to apply it to use. The qualities, therefore, of a good memory are, in the first place, to be susceptible; secondly, to be retentive; and thirdly, to be ready.

It is but rarely that these three qualities are united in the same person. We often, indeed, meet with a memory which is at once susceptible and ready; but I doubt much if such memories be commonly very retentive; for the same set of habits which are favourable to the two first qualities are adverse to the third. Those individuals, for example, who, with a view to conversation, make a constant business of informing themselves with respect to the popular topics of the day, or of turning over the ephemeral publications subservient to the amusement or to the politics of the times, are naturally led to cultivate a susceptibility and readiness of memory, but have no inducement to aim at that permanent retention of selected ideas which enables the scientific student to combine the most remote materials, and to concentrate at will, on a particular object, all the scattered lights of his experience and of his reflections. Such men (as far as my observation has reached) seldom possess a familiar or correct acquaintance even with those classical remains of our own earlier writers which have ceased to furnish topics of discourse to the circles of fashion. A stream of novelties is perpetually passing through their minds, and the faint impressions which it leaves soon vanish to make way for others, like the traces which the ebbing tide leave upon the sand. Nor is this all. In proportion as the associating principles which lay the foundation of susceptibility and readiness predominate in the memory, those which form the basis of our more solid and lasting acquisitions may be expected to be weakened, as a natural consequence of the general laws of our intellectual frame.

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