हिताहितं सुखं दुःखमायुस्तस्य हिताहितम्| मानं च तच्च यत्रोक्तमायुर्वेदः स उच्यते ||४१||
Definition and Scope of Ayurveda: Ayurveda is that which deals with good, bad, blissful and sorrowful life, and with what is wholesome and unwholesome for it, longevity, and about what Ayu (life) is in itself.
Definition of Ayu (life) and its synonyms: Ayu (life) implies the conjunction of physical body, senses, mind and soul and is known by the synonym dhari (that which preserves vitality), jivita (that which is live), nityaga (that which is in continuum), and anubandha (that which is interdependent, or a link between past life and the future life).
Superiority of Ayurveda (over other Veda): Vedic scholars regard Ayurveda as the most exalted of veda, and that which is said to be good for both the worlds for the human beings – the present and the after-life.
Samanya Vishesha Theory (similarity and dissimilarity): The principle samanya causes increase and the principle vishesha causes decrease of all the existing elements at all times, both these effects are produced by their application in the body.
सामान्यमेकत्वकरं, विशेषस्तु पृथक्त्वकृत्| तुल्यार्थता हि सामान्यं, विशेषस्तु विपर्ययः ||४५||
Samanya (is the principle which ) enables to understand similarity (between objects), and vishesha (is the principle which) enables to understand distinction(between objects). Again similarity proposes similar purpose (or action) while dissimilarity has opposite one.