लोकेऽस्मिन् द्विविधा निष्ठा पुरा प्रोक्ता मयानघ ।
ज्ञानयोगेन साङ्ख्यानां कर्मयोगेन योगिनाम् ॥ ३.३ ॥

loke’smin dvi-vidhā niṣṭhā purā proktā mayānagha ।
jnāna-yogena sāṅkhyānām karma-yogena yoginām ।। 3.3 ।।

Krishna senses Arjuna’s difficulty and discusses the question more thoroughly to clarify the relevance and indispensability of external involvement even in the context of spiritual pursuit:

Right in the beginning, had been enunciated by me the twofold discipline (nishthā) for gaining the supreme felicity (sreyas). For the knowledge-oriented sāṅkhya seekers, it is jnāna-yoga and for the yogis it is karma-yoga.

Arjuna’s apprehension that the sāṅkhya pursuit is opposed to karma pursuit is out of place, says Krishna. Man’s nature, its compulsions and the right method to honour these have been extensively studied by the Wise of this land, and the best conclusions arrived at, not now, but long ago. Thus, the right message and instructions were evolved in this country ages back, says Krishna. Spiritual pursuit does not allow any kind of conflict with human nature or its timely needs.

Thus, says Krishna, the spiritual discipline (niṣṭhā) aimed at achieving sreyas is two-fold. He uses the singular number: niṣṭhā dvividhā. The pursuit is just one, but it has two stages or phases or levels. It is like a river flowing on. Everywhere in its course, it is the same river. To begin with, it is narrow; later it becomes wider and deeper. Everywhere and every time it flows on and on to meet the sea and sea alone, to merge with it. The river may pass through many regions, joining tributaries on the way. Yet the river and its destination remain the same. When one chooses to become a seeker, he takes up the spiritual pursuit and his aim is always sreyas. His pursuit may take him through different progressive stages, but neither his seeking nor his goal changes ever.

The two stages or phases in the niṣṭhā, explains Krishna, are the jnāna-yoga and karma-yoga. It is associated with karma, external activity, to begin with. Subsequently, as the seeking gains maturity and refinement, the same nishthā becomes knowledge-attuned. Like the body growing gradually from childhood to middle age through youth, the seeker too has to grow from one level to the other. In this process, external activity does not become either an obstruction or a disharmony. The actionless Soul inhabits the actionful body. Is there any conflict in the process? Likewise, pursuing one’s nishthā associated with external activity is more a matter of need than any option or choice. And to divest the niṣṭhā of external activity will also be a sheer need and harmony at another time. Both depend upon the seeker, his level and maturity.

So Krishna categorically puts forward the assessment that getting involved in activity, while seeking the supreme good (śreyas) is not at all disharmonious. It is not to be worried about. Instead, Arjuna needs sufficient insight to evaluate matters properly and understand the relevance of external activity in the context of spiritual sādhanā. Krishna then leads the discussion to a deeper level, exposing concepts like anārambha, naiṣkarmya and siddhi. The next verse thus becomes paramount in the whole 3rd chapter.