(Latin.) A cause. Causation, among metaphysicians and logicians, is a subject of peculiar difficulty and of some danger; since, in pursuing the reasoning without due attention, some of the best men have advanced nearer the confines of infidelity than they have suspected; and mankind, ever prone to censure, have caught with eagerness at little errors, and pursued the author with the acrimony which crimes only merited. As logical disquisitions can have no place in this work, we shall fortunately escape the quicksands, though we may encounter whirlpools, on the opposite shore. Dr. Wallis, in his work on Health and Diseases, and in the last edition of this Dictionary, seemed to plume himself on establishing certainty from his disquisitions on this subject, in a science formerly conjectural; yet a more confused farrago of reasoning, with scarcely a clear determinate idea, never occurred. Disputes, however, are still less within our province, and particularly with our predecessors.
To ascertain the nature and degree of causation respecting diseases, we must first enquire what a disease is; and we shall so far anticipate that article by saying, that a disease is that condition of the human body, in which the actions of life and health proper to it are not performed, or performed imperfectly. According to this definition, the disease consists in the disordered or impeded functions; and these form, in our views, its essence. By these it is defined; by these distinguished. Authors formerly, and often at present, suppose that the disease consists in the injury which disorders or impedes the functions: thus what they consider as the disease is, strictly speaking, only the immediate cause. The difference is, indeed, merely verbal; and, when established, either plan may with equal reason be supported. If, however, it be necessary to speak of diseases as characterised by fixed indisputed marks, it must be established on a securer basis than the fluctuating systems of pathology. In this way the real disease, like the unknown quantity of the algebraist, is uncertain; but as it has distinguishing properties and a peculiar appellation, every end is attained.
Since a disease supposes a change of the body from a sound state discriminated by a given concourse of symptoms, these symptoms are the effect of that change; and the change itself the effect of a given power by whose influence it exists. Whatever, then, it be by whose influence the disease exists, is its cause. In medicine, also, it is not necessary that the cause be active, though logicians scarcely admit any other: privation, as will be seen, is a frequent cause of corporeal changes, and often a source of disease; as depriving a muscle of a portion of its nervous power, occasions violent convulsions.
The minute difference of causes in the works of many pathologists, would lead to pompous trifling, and would disgrace a science which should be distinguished by its utility alone. The first important distinction of causes is into internal and external. The former implies some defect previously rooted in the body before it breaks out into a disease, or before it becomes conspicuous by evident symptoms. To such a state, though really a morbid change, Gaubius himself, who considers what we would style the immediate cause as the disease, will not allow that appellation. External causes are, improper diet, inclement weather, sudden changes of temperature, or, indeed, whatever affects the body from without. These have been styled evident causes; and even the most empirical systems admit the utility of enquiries into them. Internal causes form the seminium morbi, the predisposition to disease; and such is the state of the human frame, that no constitution can be pronounced free from predisposition. There is, in every one, some weak organ which requires only an exciting cause to blow the spark into a flame. Thus a vomica is brougnt to a suppuration by an accidental cold, which would never otherwise have occasioned any inconvenience. This internal cause, which is often styled causa or predisponent, is roused to action by what is styled the exciting cause, causa sometimes occasio, or occasional cause. This is generally external, though not necessarily so, as we shall soon find. In general, neither of these causes alone will produce a disease, but the concurrence of both is required. If there is no predisposition, the occasional cause is harmless: without the occasio, a predisposition may exist for years harmless.
These causes have been styled, in conjunction, prin-tipia morborum, and the logical meaning of principium may be understood from Sauvages' Definition of a Cause, adopted, if we recollect rightly, from Wolfius; "Causa est, illud ex quo intelligitur alterius actualis existentia, unde discrepat a principio, ex quo non actualitas sed tantum postibilitas intelligitur."
What authors have styled the disease, or what the more correct pathologists of the present day call the proximate cause, viz. the morbid laesion, alone merits the appellation of a cause. "That only," observes Gaubius, "deserves the name of a physical cause, which so constitutes the disease that, when present, the disease exists; while it remains, the disease remains; when changed or removed, the disease is equally altered or destroyed." The lax use of the term cause among physicians has occasioned much ridicule on the art, which should have been directed against its unskilful professors: and causes,without effects; effects without causes; opposite effects from the same cause; or the same effect from opposite causes; have not been uncommonly assigned, and furnished a foundation for numerous sneers. The English reader need not look further for examples than Tristram Shandy and Hudibras.
We have spoken of the body only, without mentioning the mind. We well know their mutual influence; but have yet to learn, whether disease may consist merely in mental injury, or, indeed, whether morbid motions can originate from mind. The mental principle, which regulates the whole system, has been already spoken of. Its tranquillity and passions may be considered, as its health and diseases. These, however, are transitory, but they affect for a time the body. Joy and exultation have raised the mental powers so high that they have sunk from exhausted excitability; and the depressing passions, by lowering the irritability, have produced visceral obstructions, and every symptom of cachexy. But whatever may have been the mental source, the effect is continued from disease of body. The mental disease may be alleviated or removed; the bodily remains; nor in any instance, whatever temporary relief may arise from soothing consolation, can the disease be removed without bodily remedies.
In body, however, as in mind, the remote causes may cease to act without any change in the disease. When it is once produced, their presence or absence occasions little alteration. A person, for instance, affected by fever from marsh miasmata, may be removed to the healthiest situation without any change of his complaint; and the cold that produced rheumatism may be removed with little relief of his disorder. This, as we have said, is not the case with the proximate cause: it commences, continues, and ends, with the disease.
Another circumstance respecting causes demands our attention. We have explained two kinds of remote causes; but between these and the proximate there are many intermediate steps. There is, as we have formerly said, a series of causes and effects before the morbid laesion takes place. Thus, in the common cause of dropsy ebriety, we see that the tone of the stomach is originally destroyed. This want of irrita,bility is communicated to the liver; infarctions take place; the returning blood to the vena portae is checked in its progress; the exhalant arteries have more than their proportion of fluids; and exhalation is increased beyond what the absorbents can convey, which also seem to experience the same defective irritability. In this series there is no predisponent cause; and which is the remote cause of the disease, the diminished tone of the stomach, the infarctions of the liver, the obstruction of the vena portae, or increased exhalation ? Yet medical authors give with confidence remote and proximate causes, though the former are often various, and the latter frequently unknown. In short, in every science there is too much jargon, and too many pretensions to a knowledge that we cannot, which probably we never shall, possess.
We just now cited the cause of dropsy with a particular design: it was to adduce it as an instance, that predisponent causes, seminia morbi, do not always occur. The same occasional causes will produce the disease in the best constitution; as a fall from a house will bring on haemoptoe in the person whose lungs are most sound.
To return, then; the proximate, or the continent, cause merits our chief regard, as it alone furnishes indications of cure. This is, however, often uncertain, and in many cases unknown. If debility furnish the leading clue to explain the phenomena of fever, we can scarcely explain its operation or connection with every symptom; nor can we say why, when its cause is removed, the effect should not cease. In the disease just mentioned, dropsy, we can scarcely in any instance see the particular cause of the increased exhalation or diminished absorption ; nor, as we have found, can we rest on either any clear discriminated indications of cure. We must, therefore, often collect rules from experience, and connect them with the more obvious causes and the more certain changes in the constitution when deviating from the healty state.