ROGA NIDANA EVAM VIKRUTI VIGNANA
Deals with the study of etiology of diseases and the pathology involved in the manifestation of diseases along the lines of principlesof ayurveda.
The discipline of roga nidana finds a parallel in the modern discipline of pathology.
Pathology is the precise study and diagnosis of disease. The word pathology is from Ancient Greek πάθος, pathos which may be translated into English as either “experience” or “suffering”. and -λογία, -logia, “An account of” or “the study of”. Pathologization, to pathologize, refers to the process of defining a condition or behavior as pathological, e.g. pathological gambling. Pathologies is synonymous with diseases. The suffix “path” is used to indicate a disease, e.g. psychopath.
Pathology addresses four components of disease: cause/etiology, mechanisms of development (pathogenesis), structural alterations of cells (morphologic changes), and the consequences of changes (clinical manifestations).
Pathology is further separated into divisions, based on either the system being studied (e.g. veterinary pathology and animal disease) or the focus of the examination (e.g. forensic pathology and determining the cause of death).
The history of pathology can be traced back to antiquity when people began examining bodies. The examination of bodies led to the dissection of bodies in order to justify the cause of death. During that time, the people already began formulating today what we know as inflammation, tumors, boils, and much more.
Pathology began to develop as a subject during the 19th Century through teachers and physicians that studied pathology. They referred to it as “pathological anatomy” or “morbid anatomy.” However, pathology as a field of medicine was not recognized until the late 19th and early 20th centuries. In the 19th century, physicians realized that disease-causing pathogens, germs, created themselves and that symptoms were not the vital characteristics of a disease. Through the new information gathered regarding germ reproduction, physicians began to compare the characteristics of one germ’s symptoms as they developed within an affected individual to another germ’s characteristics and symptoms. This realization led to the foundational understanding that diseases are able to create themselves, and that they can affect human beings in unique ways. In order to determine causes of diseases, medical experts used the most common and widely accepted assumptions or symptoms of their times. This is true for those in the past and today. 
What set pathology apart from other specialties was the ability to determine a symptom with the naked eye. During the 19th century, Rudolf Virchow gave the biggest contribution to the field by introducing the procedure of analyzing tissue and cells through a microscope to pathologists. This greatly affected the discipline because it was another way to analyze objects, and it led to more advanced technological developments.
By the late 1920s to early 1930s pathology was deemed a medical specialty.  During the years following, the decision to split pathology in to sub-specialties arose. Today, anatomical, clinical, molecular, plant, forensic, oral, veterinary, dermatopathology, hematopathology, and pathology exist as medical specialties. Today, pathologists are discovering new diseases, examining exotic diseases that enter the country, and working on a solution to cure diseases such as AIDS, HIV, Herpes, cancer, and more. Thus the evolution of pathology is evidence of the real value of science, which lies in its ability to continually research and develop new methods while giving credit to those who originally developed the idea.
Clinical pathology is a medical specialty that is concerned with the diagnosis of disease based on the laboratory analysis of bodily fluids such as blood and urine, and tissues using the tools of chemistry, microbiology, hematology and molecular pathology. Clinical pathologists work in close collaboration with medical technologists, hospital administrations, and referring physicians to ensure the accuracy and optimal utilization of laboratory testing.
Clinical pathology is one of the two major divisions of pathology, the other being anatomical pathology. Often, pathologists practice both anatomical and clinical pathology, a combination sometimes known as general pathology.