Dr. Jennings was not the first to suggest the unity of disease, but he was undoubtedly the first to apply the principle of evolution to pathology. Since his day it has been the Hygienic position that there is a progressive evolution of pathology, beginning with its initial stages in infancy or early childhood and proceeding in unbroken continuity as a chain of united and interdependent sequences throughout the life of the individual, until its ending in apoplexy or cancer in middle life or thereafter.

A cold, said Tilden, "is the proximal symptom of a complex whose distal symptom is cancer, when not tuberculosis or some other fatal degenerating malady. The intermediate symptoms are the so-called acute diseases. Few people can withstand the ravages of the severe types of the interpolated so-called diseases, which are nothing more than crises of toxemia . . ." He pointed out that these crises in toxemia, which medical science has metamorphosed into special entitative and distinct individual diseases, are but the self-cleansing efforts of the body.

The persistance of pathological evolution results necessarily from persistent causation. It has been said that "God cannot make a two-year-old colt in a minute." Every growth requires time for its completion. It requires time to develop habits that influence life. Cancer, Bright's disease, apoplexy or other fatal malady, is in evolution for years. They are not of sudden development. Such factors as time, tolerance, resistance, habit and metabolic change determine the character of the symptomatic developments, although these grow, as previously stressed, out of a common basic cause. Pathologists have been so busy studying special pathology and describing the pathological fragments thus created, that they have not had time to watch the step by step and stage by stage evolution of the total pathological process.

Literally, the term pathology means a treatise on disease. It is defined as a science of disease. We are not here interested in the evolution of science, but in the evolution of disease. Evolution is a continuous development distinguished by each stage growing out of the one before and merging into the succeeding one. Commonly there is progression from simple beginnings to complex endings. The process is marked by continuity and variation.

In pathological evolution we witness a continuous growth of pathological development from simple to complex forms. Pathological evolution may be properly described as a cumulative evolution, accompanied by divergences that lead to several progressive modifications of the initial pathology. Only in a slight degree is pathological evolution orthogenic (in a straight line), but it may be in another sense, often parallel, even polytypical.

There is invariable order in the evolution of pathology. When their sequence and relationship are adequately understood, it will be seen that an unbroken line of pathological evolution reaches from its initial beginnings in infancy to the final ending in later life. Before we can understand this orderly development of abnormal changes in the structures and functions of the body, it is essential that we understand that there must first be a cause for all of these developments. Pathology is not an uncaused series of phenomena. Both the symptoms and the pathological developments must be considered as causally linked to preceding and succeeding steps in terms of chains of causes and effects. The continuity of pathological developments, once it has been adequately realized, will bring order out of the present chaos.

In each pathological development, one part is before and another part is after. When we lack a clear conception of causal relations, we fail to understand regular or invariable sequence--we are prone to attempt to explain these sequences by a superficial concomitance or accidental resemblance. So long as our attention is fixed upon merely adventitious elements in this chain of causation and we fail to recognize enervation and toxemia as basic cause, we will fail in all our efforts to remove cause.

We are asked: why must enervation precede toxemia? The answer is that, so long as nerve energy (functioning power) is adequate, excretion will keep the fluids and tissues sweet and clean and no toxemia can develop. Adequate functioning power is a sure guarantee of purity of blood. If elimination is not checked, toxemia will not evolve. This is in line with our previous statement that in every pathological development, one part is before and another part is after. The sequence is invariable. This is not to say that extraneous poisoning, such as drug poisoning, cannot occur in the absence of enervation; but this is not what is meant by toxemia, nor is such poisoning the cause of the diseases with which mankind suffers.

The popular notion that a man may be healthy one minute and sick the next, that we may dine with a healthy man at noon one day and attend his funeral the next--"sudden death" from heart disease,

cerebral hemorrhage, etc.--is based on the mistaken assumption that disease may suddenly evolve, that a serious pathological state may exist without previous preparation. In the special pathologies that have been created by the medical profession and that have received individuality and names and are regarded as entities, there is no background, no causal connection of the fully-evolved pathology with previous pathologies. One incident does not connect with another; one development does not lay the groundwork for the next. Of chronology there is but faint trace. Nowhere do we find a starting point. There is no effort to trace out what happened (developed) from time to time, from point to point, from stage to stage, in any pathological evolution.

Pathology must have a beginning somewhere and wherever this is, here is the place for us to start our studies. Studies of pathology that are carried on at necropsy are too late to have any significance for us.

In all cases of serious organic disease, such as Bright's disease, diabetes, heart disease, apoplexy, paralysis agitans, etc., etc., there have been premonitions without number, dating far back in the life of the patient, which would have enabled the patient to have prevented the evolution of the disease, had the premonitions been understood and heeded. I am convinced that detailed studies of the life and pathological history of a sufficient number of cases will enable us to predetermine the direction in which the pathological evolution is headed.

When toxemia and gastro-intestinal infection become established, the diseases of predisposition (diathesis) evolve. How do we discover that an individual has a tendency to the development of a particular disease? We discover it only when he has evolved the said disease. If a child frequently develops a sore throat, we say that he has a tendency to develop sore throat. How else would we know this? But these early crises and early stages of chronic disease would point in particular directions if we had a sufficient number of life histories of pathological evolutions to enable us to understand their meaning.