Why does Krishna describe about Ashtanga Yoga in 5.27 and 28?
Why does Krishna describe about Ashtanga Yoga in 5.27 and 28?
Three broad understandings can be there. Krishna has given the stage of perfection in the preceding verses, especially 5.25 and 26 and he is giving alternative pathways to that perfection.
After he has talked about Karma Yoga practice leading to that perfection and thus he talks about Dhyana Yoga which he will be elaborating in the 6th chapter and Bhakti Yoga which he will be elaborating in chapter 7 to 12 and which he points to in 5.29. Of course, because Krishna himself does not explicitly give any clear indications of the reason for that particular thought flow, we can only look at the context as well as the commentaries and try to figure out what is happening and see whether whatever insights we get actually make sense to us. The other point is that Krishna is focusing on the principle that the realization that is got about Brahman because he has largely used the word Brahma and not used any reference to himself till now in the 5th chapter. So, that understanding can be further deepened and evolved through the practice of Dhyana Yoga which will culminate in Bhakti Yoga and which will help a person understand that the highest realization of spiritual reality is to see not Brahman but Krishna and it is that which will give a person the ultimate unadulterated peace which is what is lacking in Arjuna’s life and which is what has led to the breakdown which led him to inquire about the Bhagavad Gita and that flow towards a deeper realization of the ultimate reality will happen in the next chapter which culminates in 6.47 with even the yogis getting the realization that the highest reality is Krishna himself.
So whereas the first analysis focuses on the progression of the paths with the future descriptions being given a preview here, the second explanation focuses on the progression of the sadhya of the understanding of the ultimate reality and this does not require the notion of a preview but this is just a progression and how to progress toward that higher realization will be described in the subsequent chapters.