13.4 तत् that, क्षेत्रम् field, यत् which, च and, यादृक् what like, च and, यद्विकारि what its modifications, यतः whence, च and, यत् what, सः He, च and, यः who, यत्प्रभावः what His powers, च and, तत् that, समासेन in brief, मे from Me, श्रृणु hear.

Commentary:
I will tell you, O Arjuna, what the field is, why the body is called the field, what are its modifications or changes in other words what transformations it undergoes, what are its properties, what effects arise in it from what causes, to whom it belongs, whether it is cultivated or whether it grows wild.That field refers to the field mentioned in verse 1.Who He is Who is that knower of the field What are His powers (Prabhavas are powers such as the power of seeing, hearing, etc.) which originate from the limiting adjuncts (such as the eys, the ears, etc.) Do thou hear My speech which describes succinctly the real nature of the field and the knower of the field in all these specific aspects.O Arjuna, I am ite sure that thou wilt clearly comprehend the truth on hearing My speech.The body is the field. The ten senses represent the ten bulls. The bulls work unceasingly day and night through the field of the objects of the senses. The mind is the supervisor. The individual soul is the tenant. The five vital airs (Pranas) are the five labourers. The Primordial Nature is the mistress of the field. This field is Her property. She Herself watches over the field vigilantly. She is endowed with the three alities. Rajas sows the seed Sattva guards it Tamas reaps the harvest. On the threshing floor or MahatTattva (the cosmic mind) with the help of the ox called time, She -- Primordial Nature -- thrashes out the corn. If the individual soul does evil actions, it sows the seeds of sin, manures with evil, reaps a crop of sin, and undergoes the pains of Samsara, viz., birth, decay, old age, sickness, and the three kinds of afflictions. If it does virtuous actions it sows the good seeds of virtue and reaps a crop of happiness.Lord Krishna now speaks very highly in the following verse of the true nature of the field and the knower of the field in order to create interest in the hearer.