And the last question which is debated is: when you can control the body and your mind, your senses and the mind, when you can control the Prakriti, then, what is the sign by which you can judge whether you have really made a progress? And Sri Krishna answer is…in sum…we shall see later in detail, but in sum the answer is that, “The more you attain to the sense of equality, and the more you perceive ‘Oneness’, the greater is your progress”:
This was the answer given in the Isha Upanishad also,
tatra ko mohaḥ kaḥ śoka ekatvam anupaśyataḥ, (Isha U. 7),
This was the answer given in the Isha Upanishad, “Where you see oneness, then all śoka, all mohaḥ is gone”. Sri Krishna repeats that answer of the Upanishad, and says that “Real progress lies when you see Oneness, and the more you see Oneness, the greater is the sense of equality, samatvaṁ”. Earlier Sri Krishna had already given the formula: samatvaṁ yoga ucyate, (II, 48), “Equality is what is called Yoga”. But now, in these two chapters Sri Krishna gives a greater detail, and points out that this samatva is based upon two things: the fact that there is Oneness in the world, samaṁ brahma, (V, 19) is the Reality, that Brahman is equal in everything, and the Knowledge of it. Even if the Brahman is one everywhere, unless you get the Knowledge of it, you cannot be free from your dualities. These two things are very important: the fact that there is samatvaṁ in the world, because samaṁ brahma,, the whole world is nothing, but spread out of the Brahman, which is one, and your Knowledge of this samaṁ brahma,; when you know that the Brahman is one. These two propositions when they are realised, then you can say that you have now made a further progress in your Sadhana.
These are the important elements in the 5th & 6th chapters, and you can see that they are nothing but elucidation of the 3rd chapter, which was further elucidate in the 4th chapter. The whole discussion is: what is the meaning of renunciation of action? And how this element of renunciation of action is demanded both by Sankhya and Yoga, both by path of Knowledge and by path of Action, as a result of which both Sankhya and Yoga are one. And therefore, Arjuna’s question as to “Tell me definitively, which one is better?” The answer is: the one, which unites Sankhya and Yoga, the Karma yoga, which is based upon the Knowledge that is the real answer; and that is the end of the 6th chapter, where you might say that fundamental teaching of the Gita is concluded.
All the rest, from 7th chapter to the 18th chapter are, you might say, the filling in blanks, further details, and still further details. As Sri Aurobindo says that if Gita was not a written scripture, but if it was a dialogue between the teacher and the pupil, then at the end of the 6th chapter the teacher would have said to the pupil: “I have given you all that is necessary for your present moment, practise all this, when you make a further progress I will come back to you and give you further”, but since it is a written book, and we are bound to read further, we cannot close the book now because the written book is given to you, so you are bound to read further, therefore all the other questions, which arise are already dealt with in these remaining chapters. So, that is the real purpose to writing 7th to 18th chapters, otherwise basically at the end of the 6th chapter, everything that is needed is given.