At the time of the Gita’s teaching, there were numerous ideas prevalent about how to achieve liberation from birth and death, as well as the role of sacrifice, the types of action the seeker should undertake, and the path of knowledge open to the practitioner of yoga. The seers of the ancient Vedas were revered and their mystical / symbolic imagery still held a very powerful sway, even though the Upanishads tried to bridge the gap to the more modern intellectual mind in various ways. It became therefore necessary for the Gita to take up and explore, widen and integrate the ideas of the time so as to provide a solution that the disciple could accept intellectually, emotionally and in a vital way in his life.
One such conception related the time and circumstance of death to the onward progression and liberation of the soul. This was based on the mystical vision of the ancient seers who developed what became known in the West as the “doctrine of signatures”, basically holding that the outer circumstances corresponded to an inner truth. Sri Aurobindo describes the correlations as set forth by the Gita: “Fire and light and smoke or mist, the day and the night, the bright fortnight of the lunar month and the dark, the northern solstice and the southern, these are the opposites. By the first in each pair the knowers of the Brahman go to the Brahman; but by the second the Yogin reaches the ‘lunar light’ and returns subsequently to human birth. These are the bright and the dark paths, called the path of the gods and the path of the fathers in the Upanishads, and the Yogin who knows them is not misled into any error.”
The Gita, after setting forth this basic guideline, nevertheless turns the seeker towards the wider truth of Oneness and ultimate “omnipresent reality” as it closes this passage: “Therefore at all times be in Yoga.”
Sri Aurobindo, Essays on the Gita, Second Series, Part I, Chapter 3, The Supreme Divine, pg. 285