Kṛṣṇa's first enriching words are Sānkhya
Śrī Kṛṣṇa is soaked in the space of completion. The first truth that comes out from Him is Sāṅkhya Yogaḥ. Kṛṣṇa is the greatest follower of Sāṅkhya Yogaḥ.
The first idea with which Kṛṣṇa is sorting out Arjuna's problem is Sāṅkhya Yoga. This means Kṛṣṇa Himself was practicing Sāṅkhya Yoga. He is established in the knowledge of Completion!
Kṛṣṇa continues: 'Never was there a time when I did not exist, nor you and all these kings, and never in the future shall any of us cease to be (2.12).' With this verse begins the essence of Gītā. This is ātmajñāna, Self-Realization, the knowledge of completion. We were there before our birth and will remain after death. It is not true that any of us will not be in the future.
Listen. You existed in the past, exist in the present and will exist in the future. Your body may change but you continue to exist. Then why do we think we will die and why do we fear death?
The past, present and future, all the three put together are eternal, Nitya or Ātman. Only when you come to the present moment do you experience Ātman, your true Self, but as of now you are constantly moving between the past and future. Kṛṣṇa says beautifully, 'Whatever dies, can never live. Whatever lives can never die.' When Kṛṣṇa says, 'You are the eternal soul,' He means that as a being, you are beyond time.
Completion, the Eternal Space in the Present
Here, your deep consciousness says that something is living in you. This quality you wrongly attribute to your body and mind. The moment you come to the present moment, you are in the eternal space of completion.
So, the first thing you need to do in life is bring completion. Kṛṣṇa does not mean that we existed in this form now, or that He was present always as Kṛṣṇa in the form with a flute and a peacock feather. He means that our spirits, which are eternal, always existed and will always exist. In our spiritual state, we are one with the universal energy, Brahman.
The essence of the second chapter, Sāṅkhya Yogaḥ is that you are the Soul, that you are Complete, that you are Divine, God. In Sāṅkhya, Completion itself is given the place of God. Completion is God!
Completion is the only methodology where you can complete with your past and future incompletions. When you do completion now, don't think that only your future will be in completion and complete. No! Even your past gets altered and complete! The moment you create the space of completion, what Kṛṣṇa declares, 'you are the eternal soul, beyond your body and mind,' becomes reality in your life.
The Only Reality Is Impermanence (2.14-2.18)
Kṛṣṇa says here that the sensory experiences are all temporary. Feelings of hot and cold, śītoṣṇa, sweet and sour, wet and dry, experiences of pain and pleasure, sukha-duḥkha are all temporary, anityāḥ. These experiences do not affect the centered person who is qualified to be enlightened, so amṛtatvāya kalpate (2.15). Such a person is qualified and ready for Enlightenment.
Kṛṣṇa says first that the spirit pervades the body—avināśi tu tad viddhi yena sarvam idaṁ tatam. His definition of body is the body-mind system. Second, the body and mind are destroyed at death—antavanta ime dehā nityasyoktāḥ śarīriṇaḥ (2.18). Third, the spirit does not die at death—vināśam avyayasyāsya na kascit kartum arhati. Fourth, He explains that the spirit is beyond our mental comprehension—anāśino 'prameyasya (2.18).
Kṛṣṇa urges Arjuna to fight, to open his eyes and see with pure patternless perception; that what he is about to do will only destroy that, which is going to perish anyway. There is no such thing as death, nābhāvo vidyate sataḥ. What dies or seems to perish is unreal, nāsato vidyate bhāvo (2.16); it had no permanent existence. What does have existence, what is truly Real, exists now, has always existed and will exist forever!
Look in! When you drill with integrity and authenticity, normal perception itself is nothing but perception of God! Because any perception will directly lead you to the space of the root of all actions, including perception! You will see that the ultimate perception, what Kṛṣṇa declares as your true nature of eternal existence and indestructible energy, becomes your reality!
Sāṅkhya is reality. What exists as Reality is perceived by you without the interference, perversions created by your powerless patterns. Sāṅkhya is the philosophy of reality, ultimate existentialism. Completion will lead you to experience that Sāṅkhya, the reality, existential reality—Tattva Satya, Satya Tattva!