Charaka

Charaka was one of the principal contributors to Ayurveda, a system of medicine and lifestyle developed in Ancient India. He is known as the compiler or editor () of the medical treatise entitled "Charaka Samhita" (). The treatise that Charaka compiled is one of the foundational treatises of classical Indian medicine and is regarded one among the Brihat-Trayee (the Greatest - trio) of Ayurveda 
Date.
After surveying and evaluating all past scholarship on the subject of Charaka's date, Meulenbeld concluded that... the author called Charaka cannot have lived later than about A.D. 150-200 and not much earlier than about 100 B.C.
Charaka has been identified as a native of Kashmir.
Charaka and the Ayurveda.
The term Charaka is a label said to apply to "wandering scholars" or "wandering physicians". According to Charaka's translations, health and disease are not predetermined and life may be prolonged by human effort and attention to lifestyle. As per Indian heritage and Ayurvedic system, prevention of all types of diseases have a more prominent place than treatment, including restructuring of lifestyle to align with the course of nature and six seasons, which will guarantee complete wellness.
Charaka seems to have been an early proponent of "prevention is better than cure" doctrine. The following statement is attributed to Acharya Charaka:
Charaka contributions to the fields of physiology, etiology and embryology have been recognised.
Charaka is generally considered as the first physician to present the concept of digestion, metabolism, and immunity. A body functions because it contains three "dosha" or principles, namely movement (vata), transformation (pitta) and lubrication & stability (kapha). The doshas correspond to the Western classification of humors, wind, bile, and phlegm. These doshas are produced when "dhatus" (blood, flesh and marrow) act upon the food eaten. For the same quantity of food eaten, one body, however, produces "dosha" in an amount different from another body. That is why one body is different from another.
Further, he stressed, illness is caused when the balance among the three doshas in a human body are disturbed. To restore the balance he prescribed medicinal drugs. Although he was aware of germs in the body, he did not give them primary importance.
Charaka studied the anatomy of the human body and various organs. He gave 360 as the total number of bones, including teeth, present in the human body. He was right when he considered heart to be a controlling centre. He claimed that the heart was connected to the entire body through 13 main channels. Apart from these channels, there were countless other ones of varying sizes which supplied not only nutrients to various tissues but also provided passage to waste products. He also claimed that any obstruction in the main channels led to a disease or deformity in the body.
Agnivesa, under the guidance of the ancient physician Atreya, had written an encyclopedic treatise in the 8th century BCE. However, it was only when Charaka revised this treatise that it gained popularity and came to be known as "Charaka Samhita". For two millennia it remained a standard work on the subject and was translated into many foreign languages, including Arabic and Latin.
Contributions.
He is the compiler or editor ("pratisaṃskartā") of the "Charaka Samhita" which is a work of several authors beginning, Charaka says, with Agniveśa. Charaka's work was later supplemented with an extra seventeen chapters added by the author Dṛḍhabala. The "Charaka Samhita" is one of the two foundational text of Ayurveda, the other being the "Sushruta Samhita". The "Charaka Samhita" contains eight parts and 120 chapters.
Influences.
According to the introductory chapter of the "Carakasaṃhitā" itself, there existed six schools of medicine, founded by the disciples of the sage Punarvasu Ātreya. Each of his disciples, Agnivesha, Bhela, Jatūkarna, Parāshara, Hārīta, and Kshārapāni, composed a medical compendium. The Agnivesha Samhitā was later revised by Charaka and it came to be known as Charaka Samhitā. The Charaka Samhitā was itself later supplemented by Dridhbala. It contains the following eight parts:
There were 8 main chapters in this book. There had been 120 sub chapters of which they all in total had 12,000 verses and description of 2,000 medicines. There were cures for diseases related to almost every body part of human body and all medicines had natural elements to cure the diseases.