No psychologist has hitherto been able, and probably it is impossible, to define madness, or to give a clearly marked indication of the boundary line between sanity and insanity. Mental soundness is merged in unsoundness by degrees of decadence which are so small as to be practically inappreciable. It is with the mind-state which precedes the development of recognized form of insanity the therapeutist and the social philosopher are chiefly interested. Although in individual cases the subject of mental derangement may, as the phrase runs, "go mad" suddenly, speaking generally insanity is a symptom occurring in the course of disease, and, commonly, not until the malady of which it is the expression has made some progress. Those mental disturbances which consist in a temporary aberration of brain function, and which are the accidents of instability, rather than the effects of developed or even developing neuroses, can scarcely be classed as insanity; although it is true, and in an important sense, that these passing storms of excitement or spells of moody depression may--acting reflexly on the cerebral and nervous centers, as all mind-states and mind-movements react--exert a morbific influence and lay the physical bases of mental disease. The consideration most practical to the community and germane to the question of public safety is, that in any and every population there must exist a dangerously large proportion of persons who are always in a condition of mind to be injuriously influenced by any force which powerfully affects them. As a matter of history, it would seem that the majority of such persons are controlled rather than morbidly excited by the opportunity of throwing themselves into any popular movement. They may suffer afterward for the stimulation they receive at the time of public commotions, but while these are in progress they link their own consciousness with that of other minds, and the tendency to develop individual eccentricities of mental action is thereby for the moment repressed or exhausted. It is in the intervals of great public excitement the peace is disturbed by the vagaries of criminals who are more or less reasonably suspected of being "insane."

It would be premature to assume that the murderer of Mr. Gold, or the man who attempted to assassinate the President of the United States of America, is insane. There are circumstances in connection with each of these tragedies which must suggest the reflection that the assailants were possibly, or even probably, of unsound mind. We do not, however, propose to discuss these features of the respective cases at this juncture. The full facts are not, as yet, ascertained; but enough is known to warrant an endeavor to clear the way for future remark by disposing of the objection that the suspected perpetrator of the Brighton outrage and the would-be assassin of the President both showed "forethought" and "method." It is a common formula for the expression of doubt as to the irresponsibility of an alleged lunatic, that there is "method in his madness." Nothing can be farther from the truth than the inference to which this observation is intended to point. It is not in the least degree necessary that a madman should be unconscious of the act he performs, or of its nature as a violation of the law of God or man; nor is it necessary that he should do the deed under an ungovernable impulse, or at the supposed bidding of God or devil, angel or fiend. The forms of mental disease to which these presumptions apply are coarse developments of insanity. Dr. Prichard was among the first of English medico-psychologists to recognize the existence of a more subtle form of disease, which he termed "moral insanity." Herbert Spencer supplied the key-note to this mystery of madness when he propounded the doctrine of "dissolution;" and Dr. Hughlings Jackson has since applied that hypothesis to the elucidation of morbid mental states and their correlated phenomena. When disorganizing--or, if we may borrow an expression from the terminology of geological science, denuding--disease attacks the mental organism, it, so to say, strips off, layer by layer, the successive strata of "habit," "principle," and "nature," which compose the character. First in order go the higher moral qualities of the mind; next those which are the result of personally formed habits; then the inherited principles of personal and social life; at length the polish which civilization gives to humanity is lost, and in the process of denudation the evolutionary elements of man's nature are progressively destroyed, until he is reduced to the level of a creature inspired by purely animal passions, and obeying the lower brutish instincts. The term "moral insanity" is accurate as far as it goes, but it expresses only the first stage in a process of dissolution which is essentially the same throughout, but which has unfortunately received different designations as its several features have been recognized and studied apart. The difference between the subject of "moral insanity" and the general paralytic, who has lost all sense of decency and lives the life of a beast, is one of degree. The practical difficulty is to convince the mere observer that forms of insanity which seem to consist in the loss of moral qualities and principles only, may be as directly the effect of brain disease as any of those grosser varieties of mental disorder which he is perfectly well able to recognize, and fully prepared to ascribe to their proper cause.

To the professional mind, at least, it will follow from what we have said that the injury to mind properties or qualities inflicted by the invasion of disease may be partial, and must in every case be determined by laws or conditions governing the progress of disease, perhaps on the lines and in the directions which have been least well guarded by educationary influences. A man may lose his faculty of forming a wise judgment long before he is deprived of the power of distinguishing between right and wrong. This is so because it is a higher attainment in moral culture to do right advisedly, than simply to perceive the right thing to do. The application of principle to conduct is an advance on the mere recognition of virtue in the concrete, or even the possession of virtue in the abstract. The question whether any past act of wrongdoing was an act of insanity does not so much depend upon the great question whether the person doing it was insane as a whole being, or whether the deed done was the outcome of passion or error, the direct fruit of limited or special disease. In short, the insanity of the act must be inferred from the morbid condition of the brain from which it sprang, rather than from the act itself. A partially disorganized--or as we prefer to say "denuded"--brain may be fully capable of sane thought, except on some one topic, and able to exercise every intellectual function except of a particular order. Or there may be mental weakness and neurotic susceptibility in regard to a special class of impressions. It would be difficult to name any form of act or submission which may not be the outcome of incipient or limited disease. The practical difficulty is to avoid, on the other hand, treating the fruits of disease as willful offenses; while, on the other, we do not allow the supposition or presumption of disease to be employed as an excuse for wrongdoing. It is, of course, clear that there may be perfect method in such madness as springs from partial or commencing brain disease; for every element in the mental process which culminates in a mad act may be sane except the inception of the idea in which the act took its rise. Thus, in the case of the suspected murderer of Mr. Gold, there may have been perfect sanity in respect to every stage of the process by which the crime was planned and carried out, and yet insanity, the effect of brain disease, in the idea by which the deed was suggested. For example, when a man is suffering from morbid suspicion, and, fixing his distrust on some individual, purposes to murder him, the intellectual processes by which he lays his plans and fulfills his morbidly conceived intention, are performed with perfect sanity, as by a sane will. It is important to recognize this. There is no difference in nature between the mental operation by which a "sane" man contrives and executes a crime, and that by which a known "lunatic" will commit the like offense. There may be as much method in the one instance as in the other, and the faculties which exhibit this method may be as sound and effective, but in the one case the idea behind the act is sane, while in the other it is insane. The brain is not one large homogeneous organ to be healthy or diseased, orderly or deranged, throughout at any one period. Inflammations, and diseases generally, which affect the brain as a whole do not commonly cause insanity properly so called. The organ of the mind is a composite, or aggregate of cells, or molecules, any number or series of which may be affected with disease while the rest remain healthy. At present we are only on the threshold of investigation concerning the physical causes of insanity, and have scarcely done more than recognize the possibility of molecular disease of the brain. Hereafter science will, probably, succeed in unveiling the obscure facts of molecular brain pathology, and enable the medical psychologist to predicate disease of recognized classes of brain elements from the special phenomena of mind disturbance. This is the line of inquiry, and the result, to which the progress already made distinctly tends. For the present, the inferences we can surely draw from known facts are very few; but prominent among the number are certain which it is all-important to recognize in view of the judgment which must hereafter be formed on the two cases now engaging public attention on both sides of the Atlantic. The existence of method in madness is no marvel, and that characteristic cannot therefore be supposed, or alleged, to weigh as evidence against the "insanity" of the criminal. The perpetrators of these heinous offenses against common right and public safety may be more or less responsible for their acts, and, so far as these are concerned, more or less sane or insane. The measure of the morbid element in their individual cases will be the health or disease of the particular part or element of the brain from which the offense sprang. The ultimate judgment formed must be determined upon the basis of scientific tests to be applied to the action of the brain alleged to be the subject of partial or incipient disease. There is nothing in the facts as they stand to supply the materials for a judgment. Precise scientific inquiry can alone solve the enigma each case presents.