Surgery:

Susruta-Samhita,  a.major  treatise on surgery, was derived not only from exhaustive observation of symptoms of diseases  and their possible treatments but also a fairly detailed knowledge of human physiology, anatomy,  and especially the internal organs. For example, in  treating ulcers or wounds, it is directed that the instruments should be introduced with the precaution of avoiding dangerous places, such as veins, bones and the like, until the pus is visible. In  the Sarnhita  there is also detailed description of different  types of  iron instruments, made by  local smiths  for extraction,  cutting etc., in terms of sharpness, shape and size. Two interesting  features  of  this treatise are: 

i)  Scrupulous attention to pre and post-surgical cleaning of  the wound, implying some empirical knowledge of  infection, and .  

ii) use of anaesthetics. While instructions are given to  bind the patient strongly so  that he could not move during the operation, it is also mentioned that he should be given wine to drink before the operation so that he might not faint and might not feel the knife.  

Thus, we find that in  Iron Age India, a scientific  approach and method was adopted in  the practice of medicine. It is not surprising that the scientific practices of Carakas and Susrutas earned the wrath and displeasure  of  the priests. This was, possibly, because their practices often contradicted the prevailing ideas of priests who earned their living by  reciting dictums such as "the gods are fond of  the obscure" or "the gods are fond of  the obscure, they detest direct observation." In the practice of medicine, the Indian physicians did not distinguish between the upper and the  lower castes in terms of  their medical attention. This was another reason why  they were not too popular with the priests.