“When men practice this threefold austerity devotedly, with enlightened faith and no desire for reward, it is said to have the nature of sattwa.” (Bhagavad Gita 17:17)
Sargeant’s translation: “This threefold austerity practiced with the highest faith by men who are not desirous of fruits and are steadfast, they regard as sattwic.”
There are some key words we should look at in this verse to appreciate its profound meaning.
Shraddhaya paraya, highest faith, means mumukshutwa: intense desire or yearning for liberation (moksha). This is the sole basis for sattwic tapasya, the primary trait of a sattwic spiritual aspirant. Although tapasya accomplishes many things in the life and mind of a tapaswin (one who engages in tapasya), not the least of which is intense purification and opening of higher faculties of awareness, all those are but the means to the single end: liberation of the spirit. Thus it is called aphalakankshibhir–without desire for personal gain (fruit) in the egoic sense, though of course moksha is the supreme attainment (paramartha). Such an aspirant is then described as yuktaih–always “in yoga,” through the continual fixing of the mind upon the Highest through the japa and meditation of Om, which is Itself the Highest.
Such are the sattwic, and such is sattwic tapasya.