The terms measles, typhoid fever, pneumonia, etc., only indicate a more or less distinctive group of symptoms--a symptom-complex. Bach "disease" is a group of symptoms that varies greatly with different patients, or under different conditions, or at different periods of life, and under different plans of care. No two cases of any "disease" are exactly alike. There are no typical cases. Text-books of medicine describe typical cases of the various so-called "diseases," but no case the practitioner ever sees ever follows these descriptions, hence, the frequent differences and mistakes in diagnosis. Tilden says: "The wide differences of opinion common to doctors in average cases are based on the unrecognized truth that so-called diseases are the summing-up symptom-complexes which vary, change, transmute, transform, and act so capriciously that even in three hours the same doctor will feel justified in changing his diagnosis and treatment. Drugs, food, the psychological influence of nurse, friend, family, doctor, hope, fear, etc., all play their part in bringing about changes in the symptom-complex, so that half a dozen days may make as many more different diagnoses." In the chapter on inflammation it was learned that inflammation is a unit. Names and forms relate, not to the process we call inflammation, but to the organ affected or to the stage of the process. Dr. Moras, in Autology, divided "diseases" into two general classes: Muco-purulent and Sero-purulent--depending on whether they had their local seat in a mucous membrane or in serous membrane. "... These two membranes assort and refine the material offered them by the organ-cells proper, and then turn out the various grades of their respective by-products through their meshes and walls and reject the unusable, which they must accumulate in the tissues to be burned up in " 'fevers' or disposed of as 'discharges' or 'effusions', or 'exudates' or 'dropsy' or 'catarrh', etc."

Carrying this thought a bit further, he said: "As the lining sac of joints is 'serous' instead of 'mucous' it is natural that the inflammatory or excessive exudate which leaks into the joints, instead of into the bronchial tubes or throat or uterine cavity, should be 'serous' instead of 'mucous' or slimy."

If then there is inflammation in the knee joint the exudate will be serous fluid, but if the inflammation is in the bronchial tube the discharge will be mucous or catarrhal. Serous inflammation is inflammation in a serous membrane and its underlying structures while catarrhal inflammation is inflammation in a mucous membrane and its underlying structures. The inflammation is the same in both cases. The cause may be the same in both cases. The differences in the "two diseases" are in the structures involved. Either of these "forms" of inflammation may become purulent--that is, there may result a breaking down of tissue. These differently located inflammations differ only in location and exciting causes.

Catarrhal inflammation may exist in any mucous surface in the body and may be either acute or chronic. Or inflammation may begin in one mucous surface and, as time passes, extend to other mucous surfaces. Thus a woman who has catarrh of the nose and throat may develop metritis, and the woman who has asthma or hay fever almost always has leucorrhea and metritis. The same constitutional derangement is at the bottom of each of these "diseases." Hay fever is but an aggravated case of catarrh; bronchial asthma is a bronchial catarrh. The symptoms in these "diseases" are fundamentally the same. The distinguishing symptoms are those of location or structure. Asthma is a special disease only because it is located in the bronchial tubes and not in the nasal passage or colon. Dr. Tilden sagely observes that if the structural changes occurring in the nasal mucosa during an attack of hay fever or in the bronchial mucosa during an attack of asthma were also to occur in the neck of the womb their presence there would afford a complete and adequate explanation of the phenomena of dysmenorrhea or painful menstruation. "This simile," he adds: "can be carried to every passage and cavity of the human body that is lined with mucous membrane. The fact is, there is no difference between a catarrhal state of one part of the body and that of some other part."

The same blood and flesh condition that causes asthma can and does cause uterine and ovarine diseases to develop and exist at the same time the asthma exists. The asthma is not the cause of the uterine troubles nor vice versa. They both stem from the same fundamental cause. Osier ascribed uterine and ovarine troubles as rare causes of an attack of asthma. Dr. Tilden rightly replied that this statement "is equivalent to saying that the hair on the dog's tail causes hair to grow on his ears."

What then of diseases of serous cavities? Are they not the same whether located in the pleura of the lungs or in the synovial membranes of the knees? The serous effusion that oozes from the pleural cavity, the ovaries and testes, or in the brain and spinal cord, or in the joints, or in the scrotum, or in dropsy, or in edema anywhere in the body is physically and chemically the same and all originate from the same blood and lymph. The same blood and flesh condition that gives rise in inflammation with effusion in one serous-lined or serous-covered organ can and does give rise to inflammation with effusion in another such organ. "Sero-purulent" diseases are a unit differing only in location and extent or degree.

The oneness and sameness of catarrhal conditions and the oneness and sameness of dropsical or edematous or serous conditions are facts which should be patent to all with intelligence enough to read English. But we go a step further. There are no differences in the "mueo-purulent" and "sero-purulent" diseases. The differences are in the organ or organs affected. Inflammation in the pleura does not differ from inflammation in the bronchial tube. In the one we have a serous exudate or effusion; in the other a mucous discharge. The pleura is a serous structure and cannot secrete mucous. The lining of the bronchial tubes is a mucous structure and cannot secrete a serous fluid. Each tissue turns out its own product from the same blood and lymph. Whether catarrhal "diseases" and edematous "diseases" are called acute or chronic, contagious or infectious makes no difference. They are all one and the same thing and all come from the same source and in the same way.

There is no essential difference between pneumonia and typhoid, encephalitis or appendicitis, tonsillitis or nephritis. Whether we have one or the other depends not upon any predilection of the toxins for the sick organ, but upon the weakness of the organ. The weaker organ is the most vulnerable. It offers least resistance to the toxins. This organic weakness that renders one organ more vulnerable to poisons is usually, if not always, a structural or anatomical weakness. Such weakness may be inherited, congenital, or the result of abuse. Chronic disease means chronic provocation.