[Disease and its course considered from a causative point of view]

The need is substantiated for differentiation between the process and course of a disease. The course of a disease may be variable, depending on critical conditions and causative factors at the beginning. Differentiation is necessary between acute and chronic diseases as well as between expected and unexpected courses (complications) of a disease. Consideration must be given to the classical differentiation between restitutio ad integrum, restitutio cum defectu and death. Special interest is focussed at the chronic disease and its relationship with the process of ageing.