The Bhagavadgita  Chapter XIII: Ksetra Ksetrajna vibhag Yoga (The Yoga of discrimination between the Field and the Knower of the Field)  

1.      Sri Bhagavan said:  This body, O son of Kunti, is spoken of as the Field (Ksetra); one who knows this, him the sages, who know the truth about both, call the Knower of the Field (Ksetrajna).

2.      Know Myself to be the Ksetrajna (Jivatma) also in all the Ksetras, Arjuna. It is the knowledge of Ksetra and Ksetrajna (i.e., of Prakrti and Purusa, Matter and Spirit) which I consider as the true knowledge.

3.      What that Ksetra is, what it is like, what are its evolutes, whence is what, and also who that Ksetrajna is and what his powers are, hear all this from Me in a nutshell.

4.      The truth about the Ksetra as well as the Ksetrajna has been sung by the seers in manifold ways; it has been stated separately in different Vedic chants and also in the conclusive and reasoned texts of the Brahmasutras.

5.      The five subtle elements (ether, air, fire, water, and earth), the ego, the intellect, Primordial Matter, the ten organs, the mind, and the five objects of sense (sound, touch, colour, taste and smell).

6.      Desire, aversion, pleasure, pain, the body, consciousness, firmness: this is the Ksetra, with its evolutes, briefly described.

7.      Absence of pride, freedom from hypocrisy, non-violence, forgiveness, straightforwardness, service of the preceptor, purity of mind and body, steadfastness, self-control,

8.      Dispassion towards the objects of senses, and absence of egoism, constant revolving in mind of the pain and evil inherent in birth, death, old age and disease;

9.      Absence of attachment, absence of self-identification with son, wife, home, etc., constant balance of mind both in favourable and unfavourable circumstances,

10.Unflinching devotion to Me through exclusive attachment of mind, living in secluded and sacred places, absence of pleasure in the company of men,

11.Fixity in self-knowledge, observing everywhere the object of true Knowledge (God): all this is declared to be Knowledge (Wisdom); what is contrary to his is called ignorance.

12.Now I shall speak to you at length about that which ought to be known and knowing which one attains immortality; that beginningless supreme Brahma is said to be neither Sat (being) nor Asat (non-being).

13.It has hands and feet everywhere, eyes, head and face, everywhere, ears everywhere.  It stands pervading all.

14.It is the perceiver of all sense-objects, though devoid of all senses; though unattached and attributeless, It is the sustainer of all and enjoyer of the qualities (the three modes of Prakrti).

15.It is without and within all beings, and constitutes both animate and inanimate creation.  By reason of Its subtlety, It is incomprehensible; It is both at hand and far away.

16.Though indivisible (like ether), It stands as if divided among beings. That knowable substance is the sustainer of beings (as Visnu), destroyer (as Rudra) and creator (as Brahma).

17.The light of all lights, It is said to be beyond the darkness of Maya.  It is knowledge itself, as well as the object of Knowledge, and is also worth attaining through Knowledge; It is specially seated in the hearts of all.

18.Thus the Ksetra as well as Knowledge and the Object of Knowledge have been briefly described; knowing this in reality, My devotee enters into My being.

19.Know Matter and Spirit to be both without beginning; and know all modifications and qualities also to be Nature-born.

20.Matter is said to be the cause of production of the body and the senses; while Spirit is said to be the cause of experience of pleasure and pain.

21.Spirit, when seated in Matter, enjoys all objects of the nature of the three Gunas (qualities) born of Matter; attachment to these qualities is the cause of his birth in good and evil wombs.

22.Spirit, even when dwelling in this body, is really transcendent (beyond the triple nature). He has been declared to be the Witness, the Guide, the Sustainer, the Experiencer (of pleasure and pain), the Supreme Lord, and the Oversoul.

23.He who thus knows Purusa (Spirit) and Prakrti (Nature) with its threefold qualities, - even though engaged in all sorts of activities, he is not born again.

24.Some by meditation behold the Self (Paramatma) in their own heart with the help of their pure reason; others by proceeding along the path of Knowledge; and others, again, by treading the path of Action.

25.Others, however, not knowing thus, take to worship by hearing from others; and they, too, who are thus intent on hearing, transcend death.

26.Arjuna, whatever being, animate or inanimate, is born, know that as emanated from the union of Ksetra (Matter) and Ksetrajna (Spirit).

27.Verily he is the seer, who sees the Supreme Lord as the only imperishable substance abiding equally in all perishable beings.

28.Seeing the same Lord dwelling equally in all, he does not kill his Self by the Self, and thereby reaches the supreme state.

29.And he really sees, who sees all actions being done in all respects only by Nature, and the self as the non-doer.

30.Whenever he perceives the diversified existence of beings as rooted in the One Supreme Being, and the projection of all beings from Him, that very moment he attains Brahma.

31.Arjuna, being without beginning and without attributes, this imperishable Paramatma (Supreme Soul), though dwelling in the body, neither acts, nor gets contaminated.

32.As the all-pervasive ether is not contaminated by reason of its subtle character, so seated everywhere in the body, the Self is not contaminated.

33.Arjuna, as the one sun illumines this whole world, so the one Atma (Spirit) illumines the whole Ksetra (Field).

34.Those who by the eye of wisdom perceive the difference between the Field and the Knower of the Field, and the negation of Prakrti with her evolutes, reach the Supreme.
 

Thus, in the Upanisad sung by the Lord, the science of Brahma, the scripture on Yoga, the dialogue between Sri Krsna and Arjuna, ends the thirteenth chapter entitled “Ksetra Ksetrajna vibhag Yoga” (The Yoga of discrimination between the Field and the Knower of the Field)