हिताहितं सुखं दुःखमायुस्तस्य हिताहितम्| 
      मानं च तच्च यत्रोक्तमायुर्वेदः स उच्यते ||४१|| 

(अर्थात जिस ग्रंथ में)

- हित आयु (जीवन के अनुकूल),

-अहित आयु' (जीवन के प्रतिकूल),

सुख आयु (स्वस्थ जीवन),

एवं दुःख आयु (रोग अवस्था) -

इनका वर्णन हो उसे आयुर्वेद कहते हैं।)

Hitahitam sukham dukhamayustasya hitahitam
Maanam cha tacha yatrokatmayurvedah sa uchyate

Ayurveda is the science of life. Ayurveda gives remedies for…

Hitayu – an advantageous life
Ahita Ayu – a disadvantageous life
Sukhayu – a happy state of health and mind
Ahitayu – an unhappy state of health and mind.

It also explains what is good and bad for life and how to measure life.