In the seventh chapter, Shri Krishna gave a detailed description of Ishvara, and stressed the importance of recognizing the infinite aspect of Ishvara. The eight chapter took a bit of a detour from that topic. In the beginning of this chapter, Arjuna raised seven questions that Shri Krishna answered in this chapter. The key question was : “how does one attain Ishvara after death” which became the main topic of this chapter.
Shri Krishna began this topic by asserting that the thought of the time of death determines our fate. If that thought is of Ishvara, we will attain Ishvara. Since we will not know when our death occurs, he advised us to meditate upon our Ishvara throughout our life so it automatically becomes our final thought. To help us cultivate this thought, Shri Krishna elaborated upon three types of meditation.
The first type of meditation was on the cosmic form of Ishvara and the second type was on the name of Ishvara, which is Om. Both these meditation techniques also required us to exercise control of our praana or life forces. Since this is beyond most of our capabilities, Shri Krishna recommended the third type of meditation which was much simpler. He advised us to remember Ishvara in any form, but do so constantly throughout our life.
So then, what happens when we die? Shri Krishna said that the universe is like an infinite cycle of creation and dissolution, symbolically depicted as the day and night of Lord Brahma. Both day and night are each 4.32 billion years long. At the end of each day of Lord Brahma, all living and non-living beings become unmanifest. When the night of Lord Brahma ends, all those beings are manifest again. In other words, they are “frozen” at the end of the day and they “thaw” in the beginning of the day. This goes on infinitely.
Having known this, our state is pitiable. We are caught in this endless cycle of creation and dissolution. Only those beings who only put forth the effort come out of this endless cycle. They attain Ishvara transcends this cycle. So, urging us to take steps towards achieving liberation is the refrain of this chapter, and of the Gita as a whole.
Towards the end of the chapter, Shri Krishna enumerated the two paths that a jeeva or soul takes after death. The first path is the dark path which is attained by those who have performed good actions on this earth. They attain the abode of the moon (heaven). After exhausting the results of their actions, they return to this world and are reborn.
The second path is the bright path which is attained by those who have practised devoted meditation on Ishvara in addition to performing good actions. They attain the abode of Lord Brahma and remain there until its dissolution when they are eventually liberation. We are encouraged to take up this path.