We have already seen in Chapter 2, “The Yoga of Analysis,” an introduction to the practice of distinguishing matter and spirit. There, the specific issue is the difference between the physical (and mental) body, and the atemporal self. This is a crucial understanding that draws on an ancient Indian philosophical tradition called Sāṅkhya. Indeed, the title of Chapter 2, sāṅkhya-yoga, points to this tradition. Here in Chapter 13 Krishna elaborates on aspects of Sāṅkhya philosophy not mentioned in Chapter 2, and there will be further aspects of this philosophical tradition explained in Chapters 14, 17, and part of Chapter 18. Here in Chapter 13, the attention turns to technical concepts, particularly “field” (kṣetra), “field-knower” (kṣetra-jña), “spirit/person” (puruṣa), and “matter/nature” (prakṛti). An understanding of these terms and their relationships fosters a deeper grasp of the distinction between the temporal body and the atemporal self, so essential for success in yoga practice. Krishna refers to this understanding as “knowledge” (jñāna), elaborating on the theme of Chapter 4; and he also responds to Arjuna’s request for him to explain further what is the “knowable” (jñeya), that which is the ultimate object of knowledge, namely spirit (brahman), also identified in this chapter as the “super-self” (paramātmā).

Krishna defines the “field” by listing its components: It is composed of gross elements, “I-am-the-doer” consciousness (ahaṁkāra), reasoning power, eleven senses (including the mind and five active functions of the body), five types of sense objects, and basic emotions such as desire, aversion, joy and misery, an amalgam of these emotions, awareness, and will (13.6-7).

Then Krishna defines “knowledge” with a list as well: Knowledge consists in a composite of several qualities, attitudes and practices, such as freedom from pride, duplicity, and violence; forgiveness, straightforwardness, honoring spiritual guides, cleanliness, steadiness, self-control, detachment from sense objects, and absence of ahaṁkāra; pondering the wretched flawedness of birth, death, old age, and disease; detachment and non-obsession with children, spouse, home, and the like; being ever equiposed in mind over wished-for and not wished-for occurrences; being fixed in devotional yoga toward bhagavān, residing in a secluded place, and not delighting in gatherings of people. Finally, knowledge is constituted of persistence in pursuit of self-knowledge, and seeing value in knowledge of truth (13.8-12).

Krishna presents the “knowable,” or the ultimate object of knowledge, in paradoxical terms (echoing some passages in Indian philosophical reflection texts, the Upaniṣads): That supreme spirit which is to be known is neither being nor nonbeing, it is both with and without senses, it is within and beyond all beings, both near and far, moving and not moving, the sustainer of all beings, the light beyond all darkness (13.13, 15-18).

The remainder of this chapter elaborates on these definitions, beginning with an explanation of how the spiritually constituted person, puruṣa, is related with matter by highlighting their differences, albeit in quite abstract terms: Whereas nature has to do with the cause-effect principle in the world, the atemporal person is the locus of experiences of happiness and distress. The person is surely situated in nature, and there he or she experiences “qualities” or “modalities” (guṇa—more about this in the next chapter) that arise out of nature, to which the person clings, experiencing good and bad births (13.21-22).

The key to this understanding is recognition that there is a superior self (paramātmā) situated within one’s body, and this is the highest person (para-puruṣa); and while there are various methods to comprehend this, it is especially possible by being dedicated to hearing these truths (13.23, 26). By such hearing, one can learn to distinguish the field (the body with its senses and emotions, etc.) from the knower of the field (the atemporal person who experiences the body) which, in turn, enables one to see that bhagavān is equally situated in all beings, neither acting nor implicated in actions (13.28, 32). Similarly, the self—the person—situated in the body, is actually not sullied by the body, just as all-pervading space is not sullied by anything within it (13.33).

In the context of discussion on Indian philosophy, Sāṅkhya and Yoga are often regarded as two distinct but complementary “systems.” Whereas in Sāṅkhya the emphasis is on discursive analysis, in Yoga the emphasis is on application of the truths of Sāṅkhya through disciplined practice. Here in the Gītā we find both systems represented, and in this chapter in particular we see analytical Sāṅkhya presented as yoga practice.