The endeavours of a man who has studied the entire Ayurveda (shastra) but fails to make a clear exposition of the same, are vain like the efforts of an ass that carries a load of sandal wood (without ever being able to enjoy its pleasing scent).
A foolish person who has gone through a large number of books without gaining any real insight into the knowledge propounded therein, is like an ass laden with logs of sandal-wood, that labours under the weight which it carries without being able to appreciate its virtue.
Hence the preceptor will clearly explain each shloka or a half or a quarter part thereof as contained in the present work, divided into a hundred and twenty chapters (as well as in the concluding portion of the Uttara-Tantram appended to it); and the student or the disciple shall attentively hear everything explained or discoursed on by the preceptor. Since it is extremely difficult to classify drugs, taste, virtue (Guna), potency (Virya), transformatory or reactionary effect 5
(Vipaka), fundamental bodily principles (Dhatu) bodily excrement (Mala), hollow viscera (Ashaya), vital parts (Marma) veins (Sira), nerves (Snayu), joints (Sandhi), bones (Asthi) and the fecundating principles of semen and ovum, and to extricate any foreign matter lodged in an ulcer), or to ascertain the nature and position of ulcers or fractures, or the palliative, curable or incurable nature of a disease, etc.; and since these subjects perplex even the profoundest intellects though a thousand times discussed and pondered over, not to speak of men of comparatively smaller intellectual capacity, hence it is imperatively obligatory on a pupil or a disciple to attentively hear the exposition of each shloka, or a half or a quarter part thereof, made by the preceptor (while studying the science of medicine).
For explanations of truths and principles quoted from other branches of (science or philosophy) and incidentally discussed in the present work, the student is referred to expositions made by the masters of those sciences or philosophies, since it is impossible to deal with all branches of science, etc. in a single book (and within so short a compass.
By the study of a single Shastra, a man can never catch the true import of this (Science of Medicine). Therefore a physician should study as many allied branches of (science or philosophy) as possible. The physician who studies the Science of Medicine from the lips of his preceptor, and practises medicine after having acquired experience in his art by constant practice, is the true physician, while any other man dabbling in the art, should be looked upon as an impostor.
The Shalya-Tantras (surgical works) written or propagated by Aupadhenava, Aurabhra, Sushruta and
Paushkalavata, are the bases of the works or Tantras written by others (Karavirya, Gopura-rakshita, etc,).