Charaka Samhita
The Charaka Samhita is believed to have arisen around 400-200 BCE. It is felt to be one of the oldest and the most important ancient authoritative writings on Ayurveda. It is not known who this person was or, if indeed, this represents the work of a "school of thought." It could have been from a group of scholars or followers of a man known as Charaka or an original composition from a single person named Charaka. This work is sometimes considered a redaction of an older and more voluminous work, Agnivesha Samhita (46,000 verses), which is no longer extant. Dridhabala, living about 400 AD, is believed to have filled in many verses of missing text (perhaps up to 20%) in the Chikitsasthana and elsewhere, which disappeared over time.
The language of Charaka is Sanskrit and its style is poetry, with meter and melody. Poetry was known to serve as a memory aid. For example, Charaka contains over 8,400 metrical verses, which are often committed to memory, in toto, by modern medical students of Ayurveda.
It presents most of the theoretical edifice of Ayurveda and concentrates on the branch of Ayurveda called kayachikitsa (internal medicine). This is largely the theory of the internal fire--of digestion--or internal medicine, in modern terms. Charaka never discusses the sub-types of pitta and kapha, but does list and describe the 5 sub-types of vata.
Seen from a greater perspective, this work seems to represent a certain value of consciousness that is different from other works. It gives more discussion about the notion that life is fundamentally a field of intelligence and pure knowledge. This field is self-aware; it is the Knower as well as the object of perception, and for Charaka this is part of what is to be treated by the physician.
The P.V. Sharma translation comes in four volumes, two of original text and two of commentary about the original work. Sharma's English version is said to be a scholarly and relatively faithful work. It has numerous appendices and an extensive index. The B. Dash / R.K. Sharma version lacks these features but does have extensive commentary incorporated in with the original text. All three translators have excellent academic or/and clinical credentials supporting their works.
Sushruta Samhita
The Sushruta Samhita presents the field of Ayurvedic surgery (shalya). This branch of medicine arose in part from the exigencies of dealing with the effects of war. This work also is said to be a redaction of oral material passed down verbally from generation to generation. It is thought to have arisen about the same time period as the Charaka Samhita, slightly after or before it according to different authorities. Its style is both prose and poetry with poetry being the greater portion.
The Sushruta Samhita, while dealing with the practice and theory of surgery, is an important source of Ayurvedic aphorisms. For example, the most comprehensive and frequently quoted definition of health is from Sushruta. This work is unique in that it discusses blood in terms of the fourth doshic principle. This work is the first to enumerate and discuss the pitta sub-doshas and the marmas. With its emphasis on pitta, surgery, and blood, this work best represents the transformational value of life.
This work, also originally written in Sanskrit, is now available in English with Devanagari. Bhishagratna's translation is English and Sanskrit. P.V. Sharma has recently written a translation with both the Sanskrit/Devanagari and English that includes Dallana's commentary. Dallana has been regarded as the most influential commentator on Sushruta's work.
Ashtanga Hridayam and Ashtanga Sangraha
Ashtanga Sangraha and Ashtanga Hridayam are the work of a person named Vagbhata. There are two works by a person or persons with this name. The Ashtanga Sangraha is nearly 40% greater in size (by verse count) and is primarily poetry with prose. The Hridayam (about 7,800 verses) is written in prose and seems to have a slightly different organization of material than the former. Both works have been dated about the same time and are thought to date after the Charaka Samhita and Sushruta Samhita (400 CE).
The exposition is relatively straightforward and also deals primarily with kayachikitsa. In this work, we see the kapha sub-doshas are listed and described for the first time, completing our modern edifice of vata, pitta, and kapha with their five sub-types. Its emphasis on treating the physiology of the body and suggestions for therapeutic use of metals and minerals means the perspective of the treatise represents the gross, material value of life more than its counterparts Charaka and Sushruta. While Charaka has entire chapters dealing with the Self, these works merely mention that the body is the home for the Self without any elaboration.
Srikantha Murthy's translation includes the Sanskrit/Devanagari for those who want to delve into the original text. S. Murthy has translated many of the ancient Ayurvedic writings into English, for which we are indebted. He has weighty credentials and brings them to bear in this work.