In this chapter, Krishna builds on the two principles introduced in the previous two chapters—detached action and sacrifice—by focusing on a third principle, transcendent knowledge (jñāna), or knowledge of spirit. Krishna emphasizes the power of transcendent knowledge, comparing it to fire (an essential component of ritual sacrifice): fire has the power to “burn to ashes” all the effects of actions performed with attachment, due to ignorance. To engage one’s powers of discernment to understand the difference between spirit and matter, and to act accordingly, is the yoga of knowledge.

Krishna focuses explicitly on the yoga of knowledge in the latter part of this chapter. First, Krishna speaks about yoga in general. Yoga, he says, is an extremely ancient teaching that he, Krishna, as bhagavān, from time to time, enters the world to renew. People tend to confuse and forget the teaching; as a consequence, dharma—the cosmic order sustained by humanity’s proper practice of duties—becomes obscured, and the whole world suffers. To restore cosmic order, bhagavan repeats the ancient yoga teaching while making it comprehensible for people living in later times (4.1-8). And the essential principle of yoga, understood as “connection”, is that humans become “connected” (or re-connected) with yogeśvara, the master of yoga, bhagavān. Such connection enables divine reciprocation, the essential principle of bhakti, devotion (more about this in later chapters) (4.10-11).

Both pious and impious ways of life find place in the economy of divine reciprocation, such that all persons receive their due, and everyone thus proceeds along Krishna’s “path”. Among humans, however, the most progressive in spiritual knowledge are those who appreciate Krishna’s—bhagavān’s— exceptional position as the unique one who, although acting, is ever free from all effects of actions’ “fruits” (results). To appreciate this feature of divinity is the foundation of liberating knowledge (jñāna); by this knowledge one comes to comprehend the difference between (binding) action and (liberating) “nonaction”. It is this kind of knowledge that “burns” away the binding effects of action, and the wise person who lives in such knowledge is truly learned (paṇḍita, 4.19), for they have true knowledge of reality, in contrast to mere belief. Such persons remain active, but all their actions are, in effect, “nonactions”, because such actions are done with an attitude of sacrifice. Such sacrificial actions-in-yoga become actions of spirit, brahman, the supreme absolute reality (4.23).

Krishna lists several traditional ways in which sacrifice—yajña—is performed. All these types of yajña have in common the act of offering as oblation something one might be inclined to keep for oneself. For example, some persons give up various goods by performing ritual worship of various celestial beings, whereas others offer oblations into the “fire” of brahman (4.25). Even the yogic discipline of restraining one’s mental functions becomes a sacrifice, in which one offers one’s sense activities as “oblations” into the (fire-like, controlled) mind. All in all, because this subject can be confusing for the inexperienced, Krishna advises one to take guidance about how to perform yajña from “seers of truth” (tattva-darśinaḥ), approaching them in a humble spirit with sincere questions, ready to offer them service (4.34). Krishna assures Arjuna that when one comprehends such knowledge of spirit, living in such knowledge, one is practicing jñāna-yoga, by which one will be ever free from confusion. Indeed, with this knowledge one will see that the countless living beings are all within the higher self (within bhagavān—Krishna, 4.35).

As this chapter ends, two analogies for this special sort of knowledge are provided, adding to the previously given analogy of knowledge-as-fire. Knowledge is compared to a boat, by which one can cross beyond all suffering (4.36); and knowledge is compared to a weapon, by which all doubts rooted in ignorance are to be slashed assunder (4.42). Thus, Krishna suggests, being engaged in jñāna-yoga is to be active in such a way that all tendencies to act in ignorance, resulting in bondage, are fully overcome as one acts with true knowledge of spirit, of reality beyond temporal existence.