ऋषिभिर्बहुधा गीतं छन्दोभिर्विविधैः पृथक्।
।।13.5।। (क्षेत्रक्षेत्रज्ञ के विषय में) ऋषियों द्वारा विभिन्न और विविध छन्दों में बहुत प्रकार से गाया गया है? तथा सम्यक् प्रकार से निश्चित किये हुये युक्तियुक्त ब्रह्मसूत्र के पदों द्वारा (अर्थात् ब्रह्म के सूचक शब्दों द्वारा) भी (वैसे ही कहा गया है)।।
The tattva or conclusive truth regarding the ksetra or field of activity being matter and the ksetrajna being the knower or witness within the field of activity have been variously described by the rsis or holy sages such as Parasara and Vasistha. In the Visnu Purana II.XIII. verse LIXX beginning aham tvancha we find: O king of the Earth we are all derived of the 24 elelments by which embodied being en masse take the bodily shape corresponding to their attraction to the three gunas or modes of material nature. In verse LXX beginning karma vasya guna we find: Verily O king the three gunas of sattva or goodness, rajas or passion and tamas or ignorance are dependent solely upon karma or reactions to ones own actions which are all the consequence of avidya or the absence of knowledge which is part of all creatures at birth. Yet in verse LXXI beginning atma suddho we find revealed: That the immortal soul is purely spiritual, imperishable, sublime, devoid of material qualities and distinctly different from prakriti or the material substratum pervading all physical existence. Similarly the Visnu Purana II.XIII.IXC beginning pindah prithag meaning: The physical body characterised by face, head, hands and body is different from the embodied being then to which of these can one refer to as I or me. Again in II.XII.CII beginning kim tvam etat chirah meaning: Art thou thy head, or thy chest, or thy stomach or thy foot and the like O king or are thou thine? And in II:XII.CIII beginning samast avayavebhyam meaning: Distinct art thou O king from all thy bodily parts and being clever determine who is the I. Both these examples postulate that matter the physical body and the spirit soul are distinctly different from each other. Vasudeva meaning the Supreme Lord Krishna is eulogised in innumerable Vedic scriptures In the Visnu Sahasra verse CXXXVII beginning indiyani mano meaning: The senses, the manas, buddhi, ego, health, strength and spirit are all ensouled by Vasudeva, both the ksetra and ksetrajna. Distinctly by various mantras of the Rig Veda, Yajur Veda, Sama Veda and Atharva Veda the distinctions between the bodily nature and the spiritual soul nature are sublimely sung. An example is found in the Tattiriya Upanisad II.I.II beginning tasmad eva etasmadatmana akasah sambhutah meaning: From the atma or eternal soul verily akasa or space has manifested , from space ether has manifested, from ether has come air, from air has come fire, from fire has come water, from water has come earth, from earth has come plants, from plants has come food, from food comes all embodied species headed by the human species. Thus the nature of the physical body has been stated. As well the subtle principle of pranas or life airs and the even subtler principle of manas or the mind and intellect have been stated in conclusion. More than the principle of the manas is the supra-subtle principle of the vijnana-maya or the conscious soul and the source of all of the above is the Supreme Lord in His localised form as paramatma the Supreme Soul within all sentient beings and even more supra-subtle than even this is His transcendental body as the composite form of all atmas in all living entities known as ananda- maya as given in the Tattiriya Upanisad II.V.II beginning: tasyaisha eva sharira atma which is the witness and monitor of living entities. Categorically as well the distinct characteristics by which the ksetra and ksetrajna exist and their manifestation by the brahman or spiritual substratum pervading all existence is revealed in many places in the Rig Veda and the Atharva Veda. Also the Vedanta Sutra verses reveal in its sublimely concise aphorisms the nature of the brahman and its relationship with the Supreme Lord. It is also called the Sariraka Sutras because of its conclusive authoritative judgement on these esoteric topics. For example in Vedanta Sutra II.III.I beginning no viyadasruteh meaning: The akasha or space is eternal because there is no Vedic evidence contrary to this and thus all decisions regarding the nature of the ksetra are formulated also in this way. Another example is seen in II.III.XVIII beginning utcrantigatyagatinam meaning: The jiva or embodied soul is infinitesimal because the Vedic scriptures state that it goes out of an old body and returns to a new body. The atma or eternal soul is superlatively conscious and such a reality formulates decisions regarding the ksetrajna. But in verse II.III.XXXX beginning kritaprayatnapekshastu vihita pratisiddha meaning: The Supreme Lord impels all jivas to act in accordance with the nature and tendency of their own self enacted previous actions and effects. Everything is under the complete control and total dominion of the Supreme Lord but He does not interfere with the freewill of the jiva although He is certainly the supreme soul of living entities. So the evidence of the ksetra and ksetrajna have been copiously expounded in various Vedic scriptures in numerous ways but now Lord Krishna will describe the same in a lucid and concise manner.