Arjuna asks Krishna seven questions: What is Brahman? What is self? What are fruitive activities? What is material manifestation? Who are demigods? Who is the Lord of sacrifice? And how can those engaged in devotional service know Krishna at the time of death?
Krishna replies “brahman” refers to the indestructible living entity (jiva): the “self” refers to the soul’s intrinsic nature of service; and “fruitive activities” means actions that develop material bodies. The material manifestation is the ever -changing physical nature; the demigods and their planets are part of the universal form of the Supreme Lord; and the Lord of sacrifice is Krishna Himself as the Super soul.
As for knowing Krishna at the time of death, it depends on one’s consciousness. The principle is this: “Whatever state of being one remembers when he quits his body, that state he will attain without fail.”
Krishna says, “whoever, at the end of life, quits his body remembering Me alone at once attains My nature without a doubt. Therefore, My dear Arjuna, you should always think of Me in the form of Krishna and at the same time carry out your prescribed duty of fighting. With your activities dedicated to Me and your mind and intelligence fixed on Me, you will attain Me without doubt.”
During each day of Brahma, all living entities become manifest, and during his night they merge into the unmanifested nature. Although there are auspicious and inauspicious times for leaving one’s body, devotees of Krishna do not care about them, for by engaging in pure devotional service to Krishna they automatically attain all the results derived from studying the Vedas or engaging in sacrifice, charity, philosophical speculation, and so on. Such pure devotees reach the Lord’s Supreme Eternal Abode.