other parts of the brain, more excited and excitable, may give false perceptions, associations, and judgments.

1549.] It will serve to illustrate this, that the collapse in sleep is more or less complete; or that the sleep, as we commonly speak, is more or less profound; and therefore, that in many cases, though sleep takes place to a considerable degree, yet certain impressions do still take effect, and exeite motions, or, if you will, sensations in the brain; but which sensations, upon account of the collapsed state of so great a part of the brain, are generally of the delirious kind, or dreams, consisting of false perceptions, associations, and judgments, that would have been corrected if the brain had been entirely excited.

Every one, I believe, has observed, that the most imperfect sleeps, are those chiefly attended with dreaming; that dreams, therefore, most commonly occur towards morning, when the complete state of sleep is passing away; and further, that dreams are most commonly excited by strong and uneasy impressions made upon the body.

I apprehend it may also be an illustration of the same thing, that, even in waking hours, we have an instance of an unequal state of excitement in the brain producing delirium. Such, I think, occurs in the case of fever. In this it is manifest, that the energy of the brain; or its excitement, is considerably diminished with respect to the animal functions and it is accordingly upon this ground that I have explained above, in 45, the delirium which so commonly attends fever. To what I have there said I shall here only add, that it may serve to confirm my doctrine, that the delirium in fever comes on at a certain period of the disease only, and that we can commonly discern its approach by a more than usual degree of it appearing in the time of the patient's falling into or coming out of sleep. It appears, therefore, that delirium, when it first comes on in fever, depends upon an inequality of excitement; and it can hardly be doubted, that the delirium which comes at length to prevail in the entirely weakened state of fevers, depends upon the same cause prevailing in a more considerable degree.

1550.] From what has been now delivered, I hope it' will be sufficiently evident, that delirium may be, and frequently is, occasioned by an inequality in the excitement of the brain.

How the different portions of the brain may at the same time be excited or collapsed in different degrees, or how the

energy of the brain may be in different degrees of force, with respect to the several animal, vital, and natural functions, I cannot pretend to explain; but it is sufficiently evident in fact, that the brain may be at one and the same time in different conditions with respect to these functions. Thus in inflammatory diseases, when by a stimulus applied to the brain the force of the vital functions is preternaturally increased, that of the animal is either little changed, or considerably diminished. On the contrary, in many cases of mania, the force of the animal functions depending always on the brain, is prodigiously increased, while the state of the vital function in the heart, is very little or not at all changed. I must therefore say again, that how difficult soever it may be to explain the mechanical or physical condition of the brain in such cases, the facts are sufficient to show that there is such an inequality as may disturb our intellectual operations.

1551.] I have thus endeavored to explain the general cause of Delirium; which is of two kinds, according as it is with, or without, pyrexia. Of the first I take no further notice here, having explained it as well as I could above in 45.

I proceed now to consider that delirium which properly belongs to the class of Vesania, and which I shall treat of under the general title of Insanity.

1552.] În entering upon this subject, it immediately occurs, that in many instances of insanity, we find, upon dissection after death, that peculiar circumstances had taken place in the general condition of the brain. In many cases, it has been found of a drier, harder, and firmer consistence, than what it is usually of in persons who had not been affected with that disease. In other cases it has been found in a more humid, soft, and flaccid state; and in the observations of the late Mr. Meckel, it has been found considerably changed in its density or specific gravity. Whether these different states have been observed to be uniformly the same over the whole of the brain, I cannot certainly learn; and I suspect the dissectors have not always accurately inquired into this circumstance: but in several instances, it appears that these states had been different in different parts of the brain; and instances of this inequality will afford a confirmation of our general doctrine.

*Memoir de Berlin pour l'annee 1764. It appeared in many instances of insane persons, that the medullary substance of the cerebrum was drier, and of a less specific gravity, than in persons who had been always of a sound judgment. Author.

But

The accurate Morgagni has observed, that in maniacal persons the medullary portion of the brain is usually dry, hard, and firm: and this he had so frequently observed, that he was disposed to consider it as generally the case. in most of the particular instances which he has given, it appears, that, for the most part, while the cerebrum was of an unusually hard and firm consistence, the cerebellum was of its usual softness, and in many of the cases it was unusually soft and flaccid. In some other cases, Morgagni observes, that while a part of the cerebrum was harder and firmer than ordinary, other parts of it were preternaturally soft.

1553.] These observations tend to confirm our general doctrine and there are others which I think will apply to the same purpose.

Upon the dissection of the bodies of persons who had labored under insanity, various organic affections have been discovered in particular parts of the brain; and it is suffi ciently probable, that such organic affections might have produced a different degree of excitement in the free and affected parts, and must have interrupted in some measure the free communication between the several parts of the brain, and in either way have occasioned insanity.

There have occurred so many instances of this kind, that I believe physicians are generally disposed to suspect orga. nic lesions of the brain to exist in almost every case of insanity.

1554.] This, however, is probably a mistake: for we know that there have been many instances of insanity, from which the persons have entirely recovered; and it is difficult to suppose that any organic lesions of the brain had in such case taken place. Such transitory cases, indeed, render it probable, that a state of excitement, changeable by various causes, had been the cause of such instances of insanity.

1555.] It is indeed further asserted, that in many instances of insane persons, their brain had been examined after death, without showing that any organic lesions had before subsisted in the brain, or finding that any morbid state of the brain then appeared. This, no doubt, may serve to show, that organic lesions had not been the cause of the disbut it does not assure us that no morbid change had taken place in the brain: for it is probable, that the dissectors were not always aware of its being the general condition of hardness and density, as different in different parts of the

ease;

brain, that was to be attended to, in order to discover the cause of the preceding disease; and therefore many of them had not with this view examined the state of the brain, as Morgagni seems carefully to have done.

1556.] Having thus endeavored to investigate the cause of insanity in general, it were to be wished that I could apply the doctrine to the distinguishing the several species of it, according as they depend upon the different state and circumstances of the brain, and thereby to the establishing of a scientific and accurately adapted method of cure. These purposes, however, appear to me to be extremely difficult to be attained; and I cannot hope to execute them here. All I can do is to make some attempts, and offer some reflections, which further observation, and greater sagacity, may hereafter render more useful.

1557.] The ingenious Dr. Arnold has been commendably employed in distinguishing the different species of insanity as they appear with respect to the mind; and his labors may hereafter prove useful, when we shall come to know something more of the different states of the brain corresponding to these different states of the mind; but at present I can make little application of his numerous distinctions. It appears to me that he has chiefly pointed out and enumerated distinctions, that are merely varieties, which can lead to little or no variety of practice: and I am especially led to form the latter conclusion, because these varieties appear to me to be often combined together, and to be often changed into one another, in the same person; in whom we must therefore suppose a general cause of the disease, which, so far as it can be known, must establish the pathology, and especially direct the practice.

1558.] In my limited views of the different states of insanity, I must go on to consider them under the two heads of Mania and Melancholia: and though I am sensible that these two genera do not comprehend the whole of the species of insanity, I am not clear in assigning the other species which may not be comprehended under those titles. I shall, however, endeavor, on proper occasions as I go along, to point them out as well as I can.

CHAPTER II.

OF MANIA, OR MADNESS.

1559.] THE circumstances which I have mentioned above in 1536, as constituting delirium in general, do more especially belong to that kind of it which I shall treat of here under the title of MANIA.

There is sometimes a false perception or imagination of things present that are not; but this is not a constant, nor even a frequent, attendant of the disease. The false judgment, is of relations long before laid up in the memory. It very often turns upon one single subject; but more commonly the mind rambles from one subject to another with an equally false judgment concerning the most part of them; and as at the same time there is commonly a false association, this increases the confusion of ideas, and therefore the false judgments. What for the most part more especially distinguishes the disease is a hurry of mind, in pursuing any thing like a train of thought, and in running from one train of thought to another. Maniacal persons are in general very irascible; but what more particularly produces their angry emotions, is, that their false judgments lead to some action which is always pushed with impetuosity and violence; when this is interrupted or restrained, they break out into violent anger and furious violence against every person near them, and upon every thing that stands in the way of their impetuous will. The false judgment often turns upon a mistaken opinion of some injury supposed to have been formerly received, or now supposed to be intended: and it is remarkable, that such an opinion is often with respect to their former dearest friends and relations; and therefore their resentment and anger are particularly directed towards these. And although this should not be the case, they commonly soon lose that respect and regard which they formerly had for their friends and relations. With all these circumstances, it will be readily perceived, that the disease must be attended very constantly with that incoherent and absurd speech we call raving. Further, with the circumstances mentioned, there is commonly joined an unusual force in all the voluntary motions; and an insensibility or resistance of the force of all impressions, and particularly a resistance of