Bg. 2.20

न जायते म्रियते वा कदाचिन्
नायं भूत्वा भविता वा न भूयः ।
अजो नित्यः शाश्वतोऽयं पुराणो
न हन्यते हन्यमाने शरीरे ॥२०॥

Text

na jāyate mriyate vā kadācin
nāyaṁ bhūtvā bhavitā vā na bhūyaḥ
ajo nityaḥ śāśvato ‘yaṁ purāṇo
na hanyate hanyamāne śarīre

Synonyms

naplugin-autotooltip__small plugin-autotooltip_bigna

never; not; are not; but not; cannot; certainly not; could not; did not; do not; does it not; does not; is not; it is not; it is not so; may not; neither; never; never does; never to be; no; no one; none; nor; not; not like that; not preceded by oṁ; not suitable; nothing; or not; shall not; should never; there is none; there is not; there should not be; was not; whether; without.
—never; jāyateplugin-autotooltip__small plugin-autotooltip_bigjayate

one becomes victorious.
—takes birth; mriyateplugin-autotooltip__small plugin-autotooltip_bigmriyate

he dies; never dies; vanquishes; will die.
—never dies; plugin-autotooltip__small plugin-autotooltip_bigva

also; alternately; and; anything else; as also; as well as; certainly; either; either, or; even though; in all probability; indeed; is either; like this; more; nor; or (in the next life); or (used sarcastically); or; otherwise; rather; the need; then.
—either; kadācitplugin-autotooltip__small plugin-autotooltip_bigkadācit

at any time (past, present or future); at any time; at some time; at that time (when Kṛṣṇa was three months old); certainly; occasionally; once; once upon a time; one day; sometimes; somewhere.
—at any time (past, present or future); naplugin-autotooltip__small plugin-autotooltip_bigna

never; not; are not; but not; cannot; certainly not; could not; did not; do not; does it not; does not; is not; it is not; it is not so; may not; neither; never; never does; never to be; no; no one; none; nor; not; not like that; not preceded by oṁ; not suitable; nothing; or not; shall not; should never; there is none; there is not; there should not be; was not; whether; without.
—never; ayamplugin-autotooltip__small plugin-autotooltip_bigayam

a person; all these (common men); all these; extraordinary it is; he (Śiva); He; Him; His; I am; in this; Kṛṣṇa; Lord Rāmacandra; of this; one; people in general; such a poor man; that; that is; the Lord; the Lord Śrī Kṛṣṇa; the same; these; this (Caitanya-caritāmṛta); this (as measured by Brahmā's duration of life); this (child within the womb); this (child); this (Kṛṣṇa); this (Lord Śiva); this (rascal); this (what has been described); this brāhmaṇa; this; this action taken by you; this animal; this Bali Mahārāja; this child; this demon; this form; this incarnation of Kapila; this is; this King; this King Pṛthu; this Kṛṣṇa; this living entity; this Lord Śrī Kṛṣṇa; this man; this one (the Supreme Lord); this one; this period; this person (Ajāmila); this person (known as Ajāmila); this person; this Personality of Godhead; this process of creation and annihilation; this soul; this Vedic knowledge; Vasudeva; Śrī Kṛṣṇa; Śukadeva Gosvāmī.
—this; bhūtvāplugin-autotooltip__small plugin-autotooltip_bigbhūtvā

again taking birth; appearing; assuming; becoming; becoming so; being elevated to that post; being so (they should not have become like that); came into being; having become; manifesting; so becoming; so being; taking birth; will become.
—came into being; bhavitāplugin-autotooltip__small plugin-autotooltip_bigbhavita

he will become; may be; shall be born; there will be; will appear; will be; will be born; will become; will come to be; will take birth; will take place; would take birth; you shall become a śūdra.
—will come to be; plugin-autotooltip__small plugin-autotooltip_bigva

also; alternately; and; anything else; as also; as well as; certainly; either; either, or; even though; in all probability; indeed; is either; like this; more; nor; or (in the next life); or (used sarcastically); or; otherwise; rather; the need; then.
—or; naplugin-autotooltip__small plugin-autotooltip_bigna

never; not; are not; but not; cannot; certainly not; could not; did not; do not; does it not; does not; is not; it is not; it is not so; may not; neither; never; never does; never to be; no; no one; none; nor; not; not like that; not preceded by oṁ; not suitable; nothing; or not; shall not; should never; there is none; there is not; there should not be; was not; whether; without.
—not; bhūyaḥplugin-autotooltip__small plugin-autotooltip_bigbhuyah

again; again and again; being; further; moreover; of increasing; on the contrary; or has come to be; still more; then again.
—or has come to be; ajaḥplugin-autotooltip__small plugin-autotooltip_bigajah

Aja; although not from a material mother; as good as Lord Brahmā; Brahmā; due to being unborn; Kṛṣṇa; Lord Aja; Lord Brahmā; Lord Śrī Kṛṣṇa; never born; Nārāyaṇa; one who is born without a material source; one who is unborn; the goat; the self-born; the self-born Brahmā; the son named Aja; the supreme unborn one; the unborn (Lord Brahmā); the unborn; the unborn Brahmā; the unborn, the Supreme Personality of Godhead; unborn; unborn, beginningless; who was not born like an ordinary human being.
—unborn; nityaḥplugin-autotooltip__small plugin-autotooltip_bignityah

always; eternal; everlasting; without birth or death.
—eternal; śāśvataḥplugin-autotooltip__small plugin-autotooltip_bigsasvatah

eternal; permanent.
—permanent; ayamplugin-autotooltip__small plugin-autotooltip_bigayam

a person; all these (common men); all these; extraordinary it is; he (Śiva); He; Him; His; I am; in this; Kṛṣṇa; Lord Rāmacandra; of this; one; people in general; such a poor man; that; that is; the Lord; the Lord Śrī Kṛṣṇa; the same; these; this (Caitanya-caritāmṛta); this (as measured by Brahmā's duration of life); this (child within the womb); this (child); this (Kṛṣṇa); this (Lord Śiva); this (rascal); this (what has been described); this brāhmaṇa; this; this action taken by you; this animal; this Bali Mahārāja; this child; this demon; this form; this incarnation of Kapila; this is; this King; this King Pṛthu; this Kṛṣṇa; this living entity; this Lord Śrī Kṛṣṇa; this man; this one (the Supreme Lord); this one; this period; this person (Ajāmila); this person (known as Ajāmila); this person; this Personality of Godhead; this process of creation and annihilation; this soul; this Vedic knowledge; Vasudeva; Śrī Kṛṣṇa; Śukadeva Gosvāmī.
—this; purāṇaḥplugin-autotooltip__small plugin-autotooltip_bigpurāṇaḥ

and the purāṇas, the supplementary Vedas; old; oldest; the oldest; the oldest, who has no other founder; the original; very old, or eternal.
—the oldest; naplugin-autotooltip__small plugin-autotooltip_bigna

never; not; are not; but not; cannot; certainly not; could not; did not; do not; does it not; does not; is not; it is not; it is not so; may not; neither; never; never does; never to be; no; no one; none; nor; not; not like that; not preceded by oṁ; not suitable; nothing; or not; shall not; should never; there is none; there is not; there should not be; was not; whether; without.
—never; hanyateplugin-autotooltip__small plugin-autotooltip_bighanyate

be killed; is killed; is victimized.
—is killed; hanyamāneplugin-autotooltip__small plugin-autotooltip_bighanyamāne

being killed.
—being killed; śarīreplugin-autotooltip__small plugin-autotooltip_bigśarīre

body; by the body; in His body; in the body; in the body of; in the material body; in the transcendental body; in the universal form; on the body; to the body; within the body.
—by the body. 

Translation

For the soul there is never birth nor death. Nor, having once been, does he ever cease to be. He is unborn, eternal, ever-existing, undying and primeval. He is not slain when the body is slain. 

Purport

Qualitatively, the small atomic fragmental part of the Supreme Spirit is one with the Supreme. He undergoes no changes like the body. Sometimes the soul is called the steady, or kūṭastha. The body is subject to six kinds of transformations. It takes its birth in the womb of the mother’s body, remains for some time, grows, produces some effects, gradually dwindles, and at last vanishes into oblivion. The soul, however, does not go through such changes. The soul is not born, but, because he takes on a material body, the body takes its birth. The soul does not take birth there, and the soul does not die. Anything which has birth also has death. And because the soul has no birth, he therefore has no past, present or future. He is eternal, ever-existing, and primeval-that is, there is no trace in history of his coming into being. Under the impression of the body, we seek the history of birth, etc., of the soul. The soul does not at any time become old, as the body does. The so-called old man, therefore, feels himself to be in the same spirit as in his childhood or youth. The changes of the body do not affect the soul. The soul does not deteriorate like a tree, nor anything material. The soul has no by-product either. The by-products of the body, namely children, are also different individual souls; and, owing to the body, they appear as children of a particular man. The body develops because of the soul’s presence, but the soul has neither offshoots nor change. Therefore, the soul is free from the six changes of the body. 

In the Kaṭha Upaniṣad also we find a similar passage which reads: 

na jāyate mriyate vā vipaścin
nāyaṁ kutaścin na vibhūva kaścit
ajo nityaḥ śāśvato ‘yaṁ purāṇo
na hanyate hanyamāne śarīre.
(Kaṭha 1.2.18)

The meaning and purport of this verse is the same as in the Bhagavad-gītā, but here in this verse there is one special word, vipaścit, which means learned or with knowledge. 

The soul is full of knowledge, or full always with consciousness. Therefore, consciousness is the symptom of the soul. Even if one does not find the soul within the heart, where he is situated, one can still understand the presence of the soul simply by the presence of consciousness. Sometimes we do not find the sun in the sky owing to clouds, or for some other reason, but the light of the sun is always there, and we are convinced that it is therefore daytime. As soon as there is a little light in the sky early in the morning, we can understand that the sun is in the sky. Similarly, since there is some consciousness in all bodies—whether man or animal—we can understand the presence of the soul. This consciousness of the soul is, however, different from the consciousness of the Supreme because the supreme consciousness is all-knowledge—past, present and future. The consciousness of the individual soul is prone to be forgetful. When he is forgetful of his real nature, he obtains education and enlightenment from the superior lessons of Kṛṣṇa. But Kṛṣṇa is not like the forgetful soul. If so, Kṛṣṇa’s teachings of Bhagavad-gītā would be useless. 

There are two kinds of souls—namely the minute particle soul (aṇu-ātmā) and the Supersoul (the vibhu-ātmā). This is also confirmed in the Kaṭha Upaniṣad in this way: 

aṇor aṇīyān mahato mahīyān
ātmāsya jantor nihito guhāyām
tam akratuḥ paśyati vīta-śoko
dhātuḥ prasādān mahimānam ātmanaḥ
(Kaṭha 1.2.20)

“Both the Supersoul [Paramātmā] and the atomic soul [jīvātmā] are situated on the same tree of the body within the same heart of the living being, and only one who has become free from all material desires as well as lamentations can, by the grace of the Supreme, understand the glories of the soul.” Kṛṣṇa is the fountainhead of the Supersoul also, as it will be disclosed in the following chapters, and Arjuna is the atomic soul, forgetful of his real nature; therefore he requires to be enlightened by Kṛṣṇa, or by His bona fide representative (the spiritual master).