Chapters 13 to 18 constitute the third cycle of the Bhagavad Gita. The first 6 chapters constitute the first cycle, 7 to 12 second cycle and 13 to 18 the third cycle.
Actually an impression can arise that chapters n°13 to 18 is a kind of a repetition and because some terms are very familiar to the Indian mentality like ‘Sattwa, Rajas and Tamas’ which appear very often in these chapters, it may even seem that these chapters are common place, almost intelligible without much attention.
One would even wonder as to whether these chapters were necessary at all for delivering the message that Sri Krishna wanted to give, because in any case it seems that by the end of 12th chapter that the message was delivered and it is true that the message is delivered because Sri Krishna wanted to explain to Arjuna why he should fight and with the 11th chapter, when Sri Krishna Himself shows this viśvarūpadarśana, and shows that He Himself has destroyed already all those who are opposing, the coming of the new kingdom, and from that state Sri Krishna commands Arjuna: “fight!”.
In that command the questions of Arjuna are all answered, namely that ‘action must proceed from the Divine’s will’. So long as you dispute in your own mind on the assumption that you are the doer, there will be always dilemmas, there will be always pros and cons and you won’t be able to decide, particularly at the critical moment, such was the moment with Arjuna now. Therefore the dilemmas can be answered only if you can rise to that level where the supreme will manifests itself directly, and when one sees that it is He who is doing and you are only the instrument. That has been achieved already by that 12th chapter. In fact even 12th chapter is a kind of a further elucidation of the answer that Sri Krishna gives in the 11th chapter.
So, what is the purpose of these last 6 chapters? And even that the impression that many things are very common place, one would ask: is there really something superb, something magnificent, something supreme in these thirteen chapters? The answer is that these chapters which seem to be common place are only in appearance so. They contain some of the most important insights and the last message that comes at the end of the 18th chapter is the real supreme word, maha vakya of the Bhagavad Gita. The supreme secret of the highest fulfilment of life is revealed at the end of the 18th chapter.
If we therefore look with a greater interest and deliberate feeling to find out the significance of these chapters, we shall find that these chapters are in a sense revelation of the Truth, revelations of a knowledge, which is a secret knowledge, minted earlier but not so well developed in those earlier chapters. It is as if in the first 6 chapters we are told that all actions ultimately end in knowledge: that in one of the supreme messages of the first 6 chapters--all actions end in knowledge--sarvaṁ karmakhilaṁ pārtha jñāne parisamāpyate (IV, 33)--all actions ultimately end in knowledge.
7th to 12th chapter, these 6 chapters take us from plane of plane of knowledge to the peak of knowledge in the 9th chapter and then unites these peaks of knowledge from where flow the waters which can quench the thirst of humanity in the deepest heart the waters of Bhakti. And at the end of the 12th chapter, you get the nectar of the Bhakti and the last line of the 12th chapter speaks of the amṛtam dharmam, of the Dharma which is immortal which can come only by the drinking of ‘ananya’ Bhakti, not only Bhakti but ‘ananya’ Bhakti, the incomparable Bhakti.
Now, if Gita were to be left at that stage, a few questions still would remain and they have to be answered. For example this very question: what is this dharmāmṛtam idaṁ? What is this immortal Dharma? That question is not elucidated in the first 12 chapters. There is of course a talk of Dharma from time to time, but this idea of dharmāmṛtam, this is the last note but a tremendous pregnant note, and this pregnancy has to be brought to the fruition.
So, you might say the first justification of these last 6 chapters is the exposition of ‘ananya’ Bhakti culminating in amṛtam dharma, by a Bhakti which is avyabhicāriṇī, this is the one term which we will come across in these last 6 chapters, Bhakti which is avyabhicāriṇī. There can be Bhakti which is full of desire, expectation, seeking of help, some kind of exploitation of the Divine, you might say, but avyabhicāriṇī, there is no exploitation of the Divine: you are given so much entirely to the Divine, nothing in you belongs to you; every atom of your being belongs to the Divine; it is as it were for the enjoyment of the Divine, not for ‘your’ enjoyment of the Divine, but you are now at the disposal of the Divine so that ‘He’ enjoys ‘you’. If you want to say, even ‘He’ wants to exploit ‘you’, instead of ‘you’ exploiting the Divine.