Concept of Rasayana in medieval works W. S. R. to naimittika Rasayana

The human beings have to pass through various changes and stages in their life time. Ageing and its physical and mental changes are so obvious and inevitable. Ayurveda being the science of life has thrown considerable light on the biology of ageing and related aspects. That knowledge is described under the discipline of Rasayana tantra. The medicine which is able to delay the ageing and cures diseases is called Rasayana. It has a comprehensive influence on the body and mind resulting into a physical, physiological and psychological improvement of an individual with prevention of ageing, improvement of mental faculties and development of immunity. Charaka has given top priority to the Rasayana and included it in Chikitsa sthana first four subchapters and in detail. Sushruta mentioned it in middle of Chikitsa sthana i.e. 27th to 30th chapters, whereas Vagbhata emphasized it in the end of the Samhita i.e. 39th chapter in Uttara tantra. Charaka dedicated four elaborated chapters to the Rasayana, while Sushruta described it in four medium sized chapters, but Vagbhata quoted it in a single chapter. Above description suggesting notable fall in the significance of this specialized branch due to the remarkable increase in the disease incidence and there by authors of the books forced to concentrate on the curative aspect of the diseases rather than preventive aspect. Keeping this in view, the study has been taken up to pickup most efficacious Rasayanas which are able to cure the diseases (Naimittika Rasayanas) as well as providing long and healthy life, especially from the medieval works.