When there is that dual nature of the mind and the body and they are separate that is disease. Both the mind and the body are not at ease. They are not feeling that oneness. If this gap is not taken care then either the mind or the body divorces the other. Both then starts to function as they are independent of each other.
Healing again is the reunion of the mind and the body and the restoration of the spirit.
When one lacks the union of the mind and the body one lacks spirit. This leads to depression and all the problems of the psyche and the physical illness. This split of mind and the body leads to the loss of homeostasis which is involved in maintaining the balance of the body. Its like a family where the mom and the dad are fighting and imagine the state of the kids. Don't mistake this as split personality.