If therefore we leave out of consideration the Uttara-tantra of Susruta, the work resolves itself mainly into a treatise on the principles of medicine as bearing on surgical diseases. It would thus appear that from a very early age, Hindu medical practitioners were divided into two classes, namely, Salya chikitsaka or surgeons and Kάyachikitsaka or physicians. The surgeons were also called Dhanvantaryia sampradaya after Dhanvantari the reputed teacher of Susruta, or from Dhanvantari the mythological surgeon of the gods. This division existed before the work of Charaka was compiled, for as pointed out by Kaviraja Brajendra-kumar Sen Gupta, Charaka, like our modern physicians, refers his readers to surgeons when surgical aid is necessary, as for example in the passage quoted below. + We may conclude, therefore, that Charaka is the oldest treatise on Medicine and Susruta the oldest treatise on Surgery now extant.

These two works, namely, Charaka and Susruta mark the highest phase of development of the Hindu system of Medicine in ancient times. Their comprehensive character and superior merit probably led, in course of time, to the extinction of the manuscripts of authors who had preceded them. Succeeding writers and practitioners came to regard these works as of divine origin and beyond the criticism of man. Accordingly they dared not add to or amend what these ancient sages had recorded regarding the general principles of medicine and special pathology, but confined their labours to making better arranged and more compendious compilations for the use of students, and to explaining or dilating upon the texts of Charaka and Susruta, while in the matter of surgical practice, there has been a gradual decline in knowledge and experience till at the present day an educated surgeon of the Dhanvantariya sampradaya is a phenomenon unknown in Hindustan.

The next compilation on Hindu Medicine is said to be the Ashtanga-hridaya-sanhita" by Sinha Gupta Sena Vagbhatta. This work is a mere compilation from Charaka and Susruta methodically arranged. It contains little or nothing that is original or that is not to be found in the works from which it was compiled. This circumstance, together with the fact of Vagbhatta being always mentioned by later writers as an old authority, seems to show that his work was compiled not long after those of Charaka and Susruta. Like these two writers he does not mention the use of mercury in the treatment of diseases.

Next in point of age, are the two works called respectively the Nidana by Madhava Kara and Chakradatta-sangraha by Chakrapani Datta. The first is a concise treatise on the causes symptoms and prognosis of diseases, compiled from various authors, and has been used from a long time as the text-book on pathology by students of Hindu Medicine throughout India. Professor Wilson is of opinion that "the Arabians of the eighth century cultivated the Hindu works on Medicine before those of the Greeks; and that the Charaka, the Susruta, and the treatise called Nidana were translated and studied by the Arabians in the days of Harun and Mansur (A. D. 773), either from the originals, or more probably from translations made at a still earlier period into the language of Persia."

The treatise called Chakradatta-sangraha, describes in detail the treatment of diseases arranged in the order in which they are described in the Nidana of Mάdhava Kara, and to which it is a companion volume. Its author deals chiefly with vegetable drugs. He gives a few prescriptions containing mercury, in which this metal is mixed with sulphur and vegetable substances, but the preparations of mercury produced by sublimation and chemical combination with salts, etc., were unknown to him. It would appear, therefore, that mercury was just coming into use in his time. He does not mention opium, so that his work, and consequently the Nidάna, must have been composed before the introduction of this drug into India by the Mussulmans.

The last great work on Hindu Medicine is that called the Bhavaprakasa, compiled by Bhava Misra. It is a comprehensive treatise, compiled from the works of preceding authors, with much additional information on the properties of drugs, accounts of new drugs, and of some new diseases, as for example the syphilis introduced into India by the Portugeese and described in this work under the name of Phiringi-roga. By the time this work was composed, opium had been largely employed in practice, the use of mercury had extended to almost all diseases, various preparations of gold, silver, tin, copper, orpiment, arsenic, etc., had come into fashion, superseding to a considerable extent the vegetable drugs of the older writers; in short Hindu pathology and therapeutics had reached their acme. Dr. Wise says that the Bhάvaprakasa was composed about three hundred years ago. It cannot, at any rate, be a much older work. China root, called Chob-chini in the vernacular, is described in it. According to Fluckiger and Hanbury the use of this drug as a remedy for syphilis was made known to the Portugueese at Goa by Chinese traders, about (A. D. 1535). Hence the Bhάvaprakasa must have been compiled after this period.

Besides the systematic treatises on the description and treatment of diseases above noticed, there are several works in Sanskrit devoted especially to the description of the synonyms and properties of individual medicines and articles of diet. The oldest treatise on this subject is the one called Rajanirghantu. It is generally ascribed to Dhanvantari, but Pundit Madhusudan Gupta estimated the age of this work at 600 years. As both mercury and opium are mentioned in this treatise, it cannot be older. Some later compilations on this subject are in general use at the present day. In the North-West Provinces, the Nirghantu, compiled by Madana-pάla, is generally perused by students. In Bengal, a very superficial compilation, under the name of Rάjavallabha, is in currency. In Orissa, a superior work, called Satkantha-ratnάbharana, is used. The progress of chemistry or rather of the art of calcining, subliming and of otherwise preparing mineral substances for medical use, was comparitively slow in the early ages. Susruta used the natural salts, such as chloride of sodium, impure carbonates of potash and soda, borax, etc.; he employed iron in anaemia, and briefly referred to the supposed properties of silver, copper, tin, lead and the precious stones, but he gave no detailed instructions regarding their calcination, preparation or administration in special diseases. Chakradatta gives some processes for reducing to powder iron, copper and talc, and a few prescriptions containing these remedies. The oldest work containing a detailed account of the calcination or preparation of the different metals (such as gold, silver, iron, mercury, copper, tin and lead), for internal use, with formulae for their administration, is I believe a concise treatise on medicinal preparations by Sarangadhara. Opium and pellitory root are mentioned in this work, hence it must have been compiled during the Mussulman period. Since then a host of works on metallic preparations and combinations have been prepared both in Bengal and the North-West Provinces, and mineral medicines have been largely adopted in the treatment of diseases. The more important parts of the information contained in these works are embodied in the Bhavaprakasa and the two works on inorganic medicines generally used in Bengal, namely, Rasendra-chintάmani and Rasendra-sarasangraha. As observed on page 54, most of the mineral medicinal preparations of the Hindus consist of their few metallic remedies combined or mixed together in an endless variety of forms. Nevertheless we cannot help admiring the ingenuity and boldness of the Hindu physicians, when we find that they were freely and properly using such powerful drugs as arsenic, mercury, iron, etc., while the Mussulman Hakims around them, with imperial patronage and the boasted learning of the west, recording such remarks regarding them as the following: -