The same Bhagavad Gita says that everything has a beginning and an end: consciousness too by that logic. Even the gods, including
Vishnu/Krishna, during Maha Pralay get destroyed and rebuilt. There is no escape for anything. Ethernal consciousness is an illusion.
> The same Bhagavad Gita says that everything has a beginning and an end
I can tell that you have not read the Gita. It never says such a thing. You're confusing the material nature with the nature of the Self.
2.12: Never was there a time when I did not exist, nor you, nor all these kings; nor in the future shall any of us cease to be.
2.16 Those who are seers of the truth have concluded that of the nonexistent [the material body] there is no endurance and of the eternal [the Self] there is no change. This they have concluded by studying the nature of both.
2.17:That which pervades the entire body you should know to be indestructible. No one is able to destroy that imperishable Self.
2.18: The material body of the indestructible, immeasurable and eternal living entity is sure to come to an end.
8.20: Yet there is another unmanifest nature, which is eternal and is transcendental to this manifested and unmanifested matter. It is supreme and is never annihilated. When all in this world is annihilated, that part remains as it is.
13.27: O chief of the Bhāratas, know that whatever you see in existence, both the moving and the nonmoving, is only a combination of the field of activities and the knower of the field.
13.33: The sky, due to its subtle nature, does not mix with anything, although it is all-pervading. Similarly, the soul situated in Brahman vision does not mix with the body, though situated in that body.
I was referring to the phrase you wrote "...The consciousness is eternal..."
None of the verse you cite says that that indestructible thing is the consciousness. That's what I was referring to. For everything that has an opposite, there would be a beginning and an end: consciousness vs unconsciousness; happiness vs sadness... . Could be something else beyond consciousness?
Even if there is something eternal, then that also has an ending, because in my experience that doesn't exist now, hence it has ended. It may come back, but doesn't mean it is eternal. Something that comes and goes means that is not eternal: it is changing too.
> None of the verse you cite says that that indestructible thing is the consciousness
The Self IS consciousness. It is sat - real, that which always is, never is not. cit - It is conscious. ananda - blissful.
Consciousness isn't what you think it is, maybe you're referring to the western definition of it which is as unreliable as anything. It's not your memory, it's not your ego, it's not your mind. These things are a part of prakṛti, or material nature and they're born of the three modes of material nature as explained in the Gita. This metaphysics is a part of the sāṁkhya philosophy.
This is subtle knowledge, it's not easy to understand these abstract ideas without a good teacher to explain it to you or some good amount of self-reflection and study. I'd highly suggest you to read Nyāya sūtra and the Bhagavad Gita (preferably with a teacher who practices these things) for a logical understanding.
> For everything that has an opposite, there would be a beginning and an end
Only the things in the material nature are composed of duality. Gita's whole point is about you, the Self, who is different from material nature, is only covered by it.
> consciousness vs unconsciousness
You're confusing the mind with consciousness. Mind is a part of material nature. There's no such thing as unconsciousness in the Gita philosophy. There are material things and there's the eternal Self, the consciousness.
> Even if there is something eternal, then that also has an ending
That's a philosophically invalid argument. Eternal by definition means that which always is. The concept of cause and effect does not apply to 'eternal' things, it is beyond time and beyond our understanding.
> because in my experience that doesn't exist now, hence it has ended.
In your experience, the future doesn't exist either, has it ended? This argument of yours is called 'hasty generalization fallacy'.
How can the Self not exist? It's literally You. The Self exists right now, it will always exist. If you think the observer dies with the material body, how did the observer come to be in the first place? An observation exists only in relation to an observer, not independently of it.
> It may come back, but doesn't mean it is eternal.
Eternal means existing forever, without beginning or end. The Self can go through different bodies, different experiences, but it 'never not exists'.
> Something that comes and goes means that is not eternal: it is changing too.
That is material nature. Intelligence, ego - false identity, the mind, sense organs, organs of actions, subtle senses and the material body and the elements that make up the material nature, all have a beginning and an end. Consciousness is even subtler than all of these things, it is not a part of the material nature, it's only covered by it.
I'd highly suggest you to study these things in detail, from a good teacher, with logic. Mental speculation is pointless, philosophical speculation provides a better understanding.
Edwin Bryant has a fantastic 8 part series on Yoga Sūtras where he goes over each thing in detail. He also has a series on nyāya sūtras which explains everything using logic. You can refer to that: https://sites.rutgers.edu/edwin-bryant/yoga-sutras/
Consciousness as the word is commonly used is a descriptor of the material processes that happen in your body. It’s not clear what you’re referring to as consciousness.
The common understanding and the philosophical understanding of consciousness are different.
While most people refer to the state of being awake and functioning as consciousness, in philosophy consciousness is the entity that is immaterial. It is the subtle life force that makes dead matter animate, It is the observer that observes. It is the irreducible immaterial entity which is mutually exclusive of material nature.
