reasoning, which makes the difference between sanity and insanity in a discourse, I cite the following:

A naval gentleman, who had been the subject of a verdict of lunacy from a writ de lunatico inquirendo, spoke to me thus: "Do you know Dr. and Dr.

Then," said he, "you know the two most obstinate fools in London. It is on their evidence I am here; it is they who are mad, not I. I defeated them in argument, and they have put me in confinement out of revenge. I will explain it to you. You are of course aware that houses describe a cycloidal curve; they are not in the same place in the evening in which they were in the morning. At least you will allow that the chimneys move, and you cannot suppose they move without the houses they are built on. Now I was proceeding to give a demonstration of this to these men, but found they had such a mere smattering of mathematics that they could not follow it; so, to conceal their ignorance, they broke off the conversation, and consigned me to a madhouse. A pretty country of liberty this, where men cannot dispute on a point of science, but, if they happen to be in a minority, they are called mad, and placed in confinement!"

On all other subjects, during a very long conversation, this gentleman evinced no sign of disturbed reason; narrated to me all the events of his life, during the eighteen years that I had lost sight of him, with perfect correctness; and discussed a variety of political and light literary topics with as much composure as ever. I took advantage of a pause at a moment when he was peculiarly tranquil, and asked him to explain to me

what he meant by chimneys making a cycloidal curve, when he very composedly began to describe the earth's course round the sun and revolution on its axis, and I saw that his morbid idea of the cycloidal curve was nothing more than a vague recollection of the nature of the cycloidal curve which a point on the earth's surface does really describe in space, from these two combined motions; but that, in the disordered state of his mind, he had confounded this with an actual change of position, from day to day, of objects on the earth's surface. He believed that a summerhouse seen from his window in a certain position in the morning, was invisible in the afternoon, though before his eyes; and when I declared it to be visible, he endeavoured to make me understand that, although strictly speaking visible, it was so only from the effect of refraction, and that the summer-house had changed its place at the rate of four minutes to a degree. By, and-by, becoming excited, he contended that the par terres in the garden had also changed their relative position while we had been talking; and then went on to the most extravagant and absurd assertions about cycloidal curves, till all power of ratiocination was lost

in confusion.

Now, if we consider this case attentively, we shall find it to be so very slight a deviation from correct conception, that we can all recollect examples of vain persons assuming acquaintance with subjects on which they are profoundly ignorant, and making mistakes of equal absurdity. If we could suppose them to persevere obstinately and permanently in their erroneous opinions, we should merely set them down as conceited fools; and if we found them incapable of compréhend

ing the absurdity when explained, we should justly call them insane; but we should not be justified in depriving them of liberty, unless we found that their collateral vagaries were injurious to others or to their own safety, which was the case with this gentleman.

I do not give this as bearing on the duality of the mind, but as one of modes of erroneous reasoning, in the hope of aiding in the effort now making by so many able writers to familiarize the public with the manifestations of mental disturbance, and thus diminish the superstitious terror with which insanity is regarded. It is seen that there is as little resemblance between the cerebral disturbance which thus distorts an established idea, and the cerebral disturbance which leads to suicide or murder, as there is between the scarlatina which merely gives a temporary headach, and the scarlatina which in a couple of days leads to delirium and to the putrefaction of all the fluids of the body, and causes death more rapidly than the plague.

CHAPTER XII.

DR. ABERCROMBIE'S TREATISE ON THE MENTAL POWERS.-CASES OF HALLUCINATION.-CEREBRAL DISTURBANCE WITHOUT DISEASE.-MORBID APPEARANCES ON DISSECTION. HALLUCINATION CONFINED TO A SINGLE POINT. -NATURE AND CAUSES OF INSANITY.-CIRCUMSTANCES IN WHICH ARGUMENT MAY BE ADDRESSED TO THE INSANE.

DR. ABERCROMBIE, in his Treatise on the Mental Powers, after citing various cases of mental impressions spontaneously arising in the brain, without the causes which in the perfectly healthy state would give rise to them, states the following instances of conscious delu sion:-"A lady under his care, in a slight feverish disorder, saw distinctly a party of ladies and gentlemen sitting round her bedchamber, and a servant handing them something on a tray. The scene continued in a greater or less degree for several days, and was varied by spectacles of castles and churches of a very brilliant appearance, as if they had been built of finely cut crystal. The whole was in this case entirely a visual phantom, for there was no hallucination of the mind. On the contrary, the patient had from the first a full impression that it was a morbid affection of vision, connected with the fever, and she amused herself and her attendants by watching and describing the changes in the scenery. Now I suspect that in this case there occurred what I have very often seen with weak-minded persons of strong imaginations, a little attempt at mystification.

The false impressions are at first real, but

if the patient be conscious of the delusion, they are a subject rather of alarm than curiosity. When the narration of them, however, is found to excite interest in the bystanders, the invalid is very apt to go on drawing on her imagination for future facts, and making up a false narrative, with no more sense of defective veracity than Walter Scott in writing his romances. How often we see this in children. The attention paid to these delusions, by patients of this class, is widely different from the philosophical examination of a man who understands the structure and functions of the brain, and exercises an enlightened curiosity in the investigation of an unusual and interesting phenomenon.

Another case, related by Dr. Abercrombie, is of a gentleman, also his patient, of irritable habit and liable to a variety of uneasy sensations in his head, who was sitting alone in his dining-room in the twilight, the door being a little open. He distinctly saw a female figure enter, wrapped in a mantle, and the face concealed by a large black bonnet. She seemed to advance a few steps towards him and then stop. He had a full conviction that the figure was an illusion of vision, and amused himself for some time by watching it; at the same time observing that he could see through the figure so as to perceive the lock of the door and other objects behind it. At length, when he moved his body a little forward, it disappeared.

The appearances in these two cases were entirely visual illusions, and probably consisted of the renewal of real scenes or figures in a manner somewhat analogous to those in Dr. Ferriar's case, though the renewal took place after a longer interval. degree of hallucination of mind, so

When there is any

that the phantasm