In the evolution of the human consciousness there was a time when there was no real division between the body consciousness and the identity’s overall consciousness, but with the emergence of the ego “I” awareness, there began an every increasing division between the two. At that time, illness was nowhere near as prevalent as it is now, and frankly, witch doctors and shaman quite ably served the early communities with surprisingly good results. They had an innate understanding of the link between illness and the state of the mind. At times they would literally scare the illness out of the seemingly possessed unfortunate patient because in those early times, illness, sickness and infirmity was often viewed as being possessed by evil spirits.
Understanding the mind body link, the earliest practitioners, both healers and patients, did not need to have a Harvard education and a wall full of impressive degrees to know that one way or the other, almost all illness was the result of a discordant mental state whether it be from unhealthy beliefs, displeased spirits or psychological demons, projected outward from within. Here I speak in generalities to some extent, but under most conditions, the advent of modern day illness is the chosen method of the physical body to alert the ego consciousness (the exterior self) that something is wrong inside.
As the evolving ego consciousness began to focus more intently on our physical three dimensional reality, more and more it had to constantly assess and learn to deal with an ever more complicated world. Mankind was emerging from a time when the only things one needed to deal with in everyday life was the knowledge and location of the nearest hostile tribe, the timing of the next animal migration and where to find the sweetest fruit and tubers. In short, in those early times, living was a "no-brainer" compared to the vast amounts of stimuli facing today’s modern society. At least then, you knew who or what was going to kill you, now it’s a toss up, and the line forms to the rear.
Our civilization, as it became more complex, more intricate, more developed and more multi faceted, it required more and more concentration just to maintain a balance in a challenging system of reality like none other. It would now take every bit of our mental acuity as a civilization to maintain a psychological balance to hold our stance in this ‘Earth Reality”. Well, no surprise then, that in a way, sometime in the not so ancient past the ego began more and more to divorce itself from the concerns of the inner personality from which it had recently emerged.
It goes without saying that we are both psychological and physical beings, temporarily adopting human form, creating a psychological overlay of matter over form which permits the inner self to delve into a medium of reality previously quite unfamiliar to it. It has accreted physical matter upon and over psychological patterns, creating new form, in order to learn, grow, evolve and gain a different kind of experience than would be available without this quite unique adventure into consciousness.
In light of the advent of increasingly complex societies and accompanying inherent problems and challenges, the inner self began to feel an increasing need to find a way to alert and relay its distress signals to the attention of the ego consciousness so they could be addressed and corrected in a satisfactory manner. The method adopted could not be simpler. The inner self had to establish a link between mental and physical balance and bodily illness. The body would act as a flesh and blood barometer indicating the state of health of the physical personality.