disease, having been once compos mentis, pertinaciously adheres to some delusive idea, in opposition to the plainest evidence of its falsity; and endeavours, by the most ingenious arguments, however fallacious they may be, to support his opinion (d).

5. The true criterion, the true test, of the absence or presence of insanity, where there is no frenzy or raving madness, seems to be the absence or presence of what, used in a certain sense of it, may be comprised in a single term, namely, delusion. Wherever the patient once conceives something extravagant to exist, which has still no existence whatever but in his own heated imagination; and, wherever, at the same time, having once so conceived, he is incapable of being, or, at least, of being permanently reasoned out of that conception-such a patient is said to be under a delu

sion.

Insane delusion consists in the belief of facts which no rational person would have believed. This delusion may sometimes exist on one or two particular subjects, though, generally, there are other concomitant circumstances, such as eccentricity, irritability, violence, suspicion, exaggeration, inconsistency, and other marks and symptoms, which may tend to confirm the existence of delusion, and to establish its insane character.

The absence or presence of delusion, so understood, forms the true and only test, or criterion, of absent or present insanity. In short, delusion in that sense of it, and insanity, seem to be almost, if not altogether, convertible terms; so that a patient under a delusion, so understood, on any subject or subjects, in any degree, is, for that reason essentially mad or insane on such subject or subjects in that degree. On the contrary, in the absence of any such delusion, with whatever extravagances a supposed lunatic may be justly chargeable, and how like soever to a real madman he may either speak or act on some or on all subjects; still, in the absence of any thing in the nature of delusion, so understood, the supposed lunatic is not properly or essentially insane (e).

(d) Willis on Mental Derangement, pp. 221, 228; Dr. Morison's Outlines of Lectures on Mental Dis

eases, p. 17.

(e) Per Sir J. Nicholl, in Dew v. Clark, 3 Add 90,91.

In most cases of delusion, the delusion founds itself, originally, on some slight circumstance, the magnifying of which, beyond all reasonable bounds, is nearly or quite as good in proof of its being a delusion, as the taking up some absurd prejudice, which is utterly unfounded, or that rests upon no basis. If one whose eyesight is slightly affected, conceives, and in spite of all argument persists in and acts under a conception that he is totally blind, this is as perfectly a delusion on the part of that person, as if nothing at all were the matter with his eyes. If another, the proprietor of a large domain, on the loss of a comparatively small portion, is convinced to himself that he has been deprived of the whole of it; if he persists in that conviction, in spite both of argument and of evidence to the contrary-not only so, if he suffers that conviction to poison and preclude his enjoyment of the ample portion that still remains to him, during and throughout all the rest of his life-this is as essentially a delusion on the part of such person, as if he was still in possession of every acre of his original estate.

So, if the parent of a child, really blameable to a certain extent in some particulars, takes occasion from this to fancy her a "fiend, a monster, an incarnate devil;" if, moreover, he be found through his whole life acting under and upon that conception, such a parent is as much in a state of morbid delusion, and so of insanity in regard to that child, as if the child's conduct were wholly irreproachable (ƒ).

6. When delusion exists in the mind of a person on one or more particular subjects, it is termed in law partial insanity. In that sense the term is used by Lord Hale, who says, there is a partial insanity of mind, and a total insanity. The former is either in respect to things, quoad hoc vel illud insanire; some persons, that have a competent use of reason in respect of some subjects, are yet under a particular dementia in respect of some particular discourses, subjects, or applications; or else it is partial in respect of degrees; and this is the condition of very many, especially melancholy persons, who, for the most part, discover their defect in ex

(f) Per Sir J. Nicholl, in Dew v. Clark, 3 Add. 180, 181; and report of S. C. by Hagg. 27.

cessive fears and griefs, and yet are not wholly destitute of the use of reason; and this partial insanity seems not to excuse them in the committing of any offence for its matter capital; for doubtless, most persons that are felons of themselves, and others, are under a degree of partial insanity when they commit these offences. It is very difficult to define the invisible line that divides perfect and partial insanity; but it must rest upon circumstances, duly to be weighed and considered both by judge and jury; lest, on the one side, there be a kind of inhumanity towards the defects of human nature; or, on the other side, too great an indulgence given to great crimes: and the same learned judge adds, "that the best measure is this-such a person as labouring under melancholy distempers hath yet ordinarily as great understanding, as ordinarily a child of fourteen years hath, is such a person as may be guilty of treason or felony (g).”

The law recognises partial insanity; and, in civil cases, this partial insanity, if existing at the time the act is done, if there be no clear lucid interval, invalidates the act, though not directly connected with the act itself; but, in criminal acts, it does not excuse from responsibility, unless the insanity is proved to be the very cause of the act (h). It is stated in Hadfield's case, that there is a wide distinction between civil and criminal cases. If, in the former, a man appears upon the evidence to be non compos mentis, the law avoids his act, though it cannot be traced or connected with the morbid imagination which constitutes his disease, and which may be extremely partial in its influence upon conduct; but, to deliver a man from responsibility for crimes, above all, for crimes of great atrocity, this rule does not apply, however well established when property only is concerned; but the relation between the disease and the act should be apparent. And a party ought not to be protected from answering criminally for acts which can justly be ascribed to malignant motives, and not to the dominion of disease.

(g) 1 Hale's P. C. 30.

(h) This doctrine is recognised by Sir J. Nicholl in Dew v. Clark, re

ported by Hagg. p. 13; S. C. 3 Add 93.

The doctrine of partial insanity is applicable to civil cases generally, although an attempt to shew the contrary was made in a recent case (i), and will avail to defeat a will, the direct offspring of that partial insanity, both in the Courts of common law, and in the Ecclesiastical Court (k).

In all the cases of lunacy which have filled Westminster Hall with the most complicated considerations, the subjects of them have not only had memory, and a perfect knowledge and recollection of all the relations they stood in towards others, and of the acts and circumstances of their lives, but have, in general, been remarkable for subtilty and acuteness. Defects in their reasonings have seldom been traceable, the disease consisting in the delusive sources of thought; all their deductions within the scope of the malady being founded upon the immoveable assumption of matters as realities, either without any foundation whatsoever, or so distorted and disfigured by fancy, as to be nearly the same thing as its creation. It is true, indeed, that in some, perhaps in many cases, the human mind is stormed in its citadel, and laid prostrate under the stroke of phrensy: these unhappy sufferers, however, are not considered by physicians as maniacs, but to be in a state of delirium, as from fever. There, indeed, all the ideas are overwhelmed, for reason is not merely disturbed, but driven wholly from her seat. Such unhappy patients are unconscious, therefore, except at short intervals, even of external objects; or, at least, are wholly incapable of considering their relations. Such persons, and such persons alone, (except idiots), are wholly deprived of their understandings. These cases, however, are not only extremely rare, but never can become the subjects of judicial difficulty. There can be but one judgment concerning them. In other cases, reason is not driven from her seat, but distraction sits down upon it along with her, holds her trembling upon it, and frightens her from her propriety. Such patients are victims to delusions of the most

(i) 3 Add. 93.

(k) Greenwood's case, 13 Ves. 89; 3 Br. C. C. 444; Dew v. Clark, 1 Add.

274; S. C. 3 Add. 79; Heath v. Watts, Prerog. 1798; Deleg. 1800. See post, ch. vii. sect. 6.

alarming description, which so overpower the faculties, and usurp so firmly the place of realities, as not to be dislodged or shaken by the organs of perception and sense; in such cases the images frequently vary, but on the same subject are generally of the same terrific character. Here, too, no judicial difficulties can present themselves; for who could balance upon the judgment to be pronounced in cases of such extreme disease?

Another class, branching out into almost infinite subdivisions, under which, indeed, the former, and every case of insanity may be classed, is, where the delusions are not of that frightful character, but infinitely various, and often extremely circumscribed; yet, where imagination (within the bounds of the malady) still holds the most uncontrollable dominion over reality and fact: and these are the cases which frequently mock the wisdom of the wisest in judicial trials, because, such persons often reason with a subtlety which puts in the shade the ordinary conceptions of mankind; their conclusions are just, and frequently profound; but the premises from which they reason, when within the range of the malady, are uniformly false;-not false from any defect of knowledge or judgment, but because a delusive image, the inseparable companion of real insanity, is thrust upon the subjugated understanding, incapable of resistance because unconscious of attack (i).

Extraordinary instances of delusion on particular subjects with apparent general sanity are related. Two cases of this kind were mentioned by Lord Erskine, who said, that he examined, during the greater part of a day, an unfortunate gentleman, who had indicted his brother, together with a keeper of a madhouse at Hoxton, for having imprisoned him as a lunatic, whilst, according to his evidence, he was in his perfect senses. Lord Erskine said, that he was, unfortunately, not instructed in what the lunacy consisted, although his instructions left him no doubt of the fact; but, not having the clue, the lunatic completely foiled him in every attempt to expose his infirmity, although he left no means unemployed, which long experience dictated, but without the smallest effect. The

(i) Erskine's speech in Hadfield's trial, 27 Vol. Howell's St. Tr. 1313.