In chapter 14, Krishna explained how a living entity is captured within its field of activities through the all-encompassing modes of material nature. Using the example of a reflected banyan tree, Krishna now depicts the entire span of the field.
It is said (prāhur) that there is an imperishable banyan tree (aśvatthaṁ avyayam) with its roots up (ūrdhva-mūlam) and its branches down (adhaḥ-śākham) whose (yasya) leaves (parṇāni) are the Vedic hymns (chandāṁsi). One who knows this tree (yas taṁ veda) is the knower of the Vedas (sa veda-vit). (BG 15.1) Its branches (tasya śākhā) extend (prasṛtās) down and up (adhaś cordhvaṁ), grown by the three modes of material nature (guṇa-pravṛddhā) with its twigs being the sense objects (viṣaya-pravālāḥ). Its roots (mūlāni), also (ca) extending (anusantatāni) down (adhaś), are bound to the fruitive actions (karmānubandhīni) in human society (manuṣya-loke). (BG 15.2)
In this world (iha), neither (na) the form of this tree (rūpam asya) as such (tathā) is perceived (upalabhyate), nor its end (nānto), nor its beginning (na cādir), nor its foundation (na ca sampratiṣṭhā). Cutting down (chittvā) this (enaṁ) very strongly rooted (su-virūḍha-mūlam) banyan tree (aśvattham) with a firm (dṛḍhena) weapon of detachment (asaṅga-śastreṇa), thereafter (tataḥ), one must seek (parimārgitavyaṁ) that place (padaṁ tat) from where, having gone (yasmin gatā), one never returns (na nivartanti bhūyaḥ). And (ca), one must submit (prapadye) to that Primeval (adyaṁ) Person alone (tam eva puruṣaṁ) from whom every initiative (pravṛttiḥ) has extended (yataḥ prasṛtā) since time immemorial (purāṇī). (BG 15.3-4)
Krishna next elaborates on the qualifications necessary to escape the illusory banyan tree and go to the eternal spiritual abode. Free from false prestige (nirmāna) and illusion (mohā), having conquered the fault of association [with matter] (jita-saṅga-doṣā), eternally fixed on the Higher Self (adhyātma-nityā), disassociated (vinivṛtta) from lusty desires (kāmāḥ), liberated (vimuktāḥ) from the dualities (dvandvair) like happiness and distress (sukha-duḥkha-saṁjñair), the unbewildered (amūḍhāḥ) go (gacchanty) to that (tat) eternal (avyayaṁ) place (padam). (BG 15.5)