samadhi state
There is a fourth state that we have not experienced in our life, where we have no flow of thoughts yet we have 'I' consciousness, pure 'I' consciousness. This is samādhi, thoughtless awareness — turīya avastha, ātma jñāna, brahma jñāna, Self-realization, nirvāna, ātma bhūti, state of the Divine, nityānanda consciousness, eternal bliss! All these words refer to the state where we have pure awareness but no thoughts, where we exist without body and mind. Jāgrat, svapna, suṣupti, in these three states, we live with the body and mind. In jāgrat, we live with the body that we have now — the sthūla śarīra or gross body. In svapna, we live with the sūkṣma śarīra or subtle body; please understand in the dream state also we assume a body. That is why we are able to travel in our dreams. For example, we fall asleep in Los Angeles but suddenly dream we are in Bharat! It means we travel with a body, a subtle body called sūkṣma śarīra.
a glimpse of consciousness
In deep sleep, we assume a body called the causal body, kāraṇa śarīra. In turīya state, we experience boundarilessness, bodylessness. There we have pure 'I' consciousness, with 'I' but without thoughts.
Vivekananda says, 'If you experience even a single glimpse of this consciousness when you are alive, the same thing automatically repeats when you leave the body. You leave the body in samādhi.' All spiritual practices directly or indirectly aim at achieving this state where we exist with the awareness of 'I' , but without the consciousness of body and mind. That is why Kṛṣṇa says that if we experience at least one moment of consciousness beyond the body and mind, we can choose our next life in a relaxed way.
a glimpse of consciousness
If we have not lived a single moment of our life without the feeling of being the body and mind, we cannot be without the body and mind once we die. So once we die, we immediately try to catch hold of another body.
Even a glimpse of consciousness, a moment of realization, a single moment of thoughtless awareness, when you live with the body and mind is enough. Actually, if you achieve one glimpse of thoughtless awareness, you achieve whatever has to be achieved in life.