IntroductionBhagavad Gita is fundamentally built on the platform that the soul is eternal and the body is temporary and that both are unique and distinct but co-existing. The entire theme the reader will encounter in the later chapters are founded on this fundamental idea. If we miss this point, Bhagavad Gita will seem incompatible with practical life. If we assimilate this point, Bhagavad Gita is the most practical book in life. So it is a matter of consciousness, are we reading the book as a spiritual being or a material being?
Krishna then envelops layers of thought (like an onion) around the body-soul paradigm. The first layer is the idea of doing one's duty. Krishna urges Arjuna to perform one's duty. He urges him to rise above the three modes to perform duty with equanimity of mind to success or failure, honor or dishonor, heat or cold etc. This equanimity of mind, Krishna tells is the foundation of yoga. To perform one's duty without attachment to the fruits of one's labor is superior to performing one's duty with attachment. Krishna also warns Arjuna that it is better to doing one's duty faultily (that is with attachment) than without doing it at all.
Krishna envelopes a further layer of thought called brahman or brahma-nirvana. He says that as one performs one's duty without attachment to the fruits of labor thus maintaining equanimity of mind in yoga, and also by controlling the breathing process within ashtanga (eight fold system), one is able to attain to the pure state of consciousness called brahman. In this state Krishna says one can find happiness in the self. The stage of brahman is above the stage of performing result-free duty.
Knowledge of this world
On the other side, Krishna also shows the contrast of lifestyle of one who is on the bodily platform, those who are mired by the three modes of goodness, passion and ignorance. Constantly harassed by the modes, the jiva is shuttling up and down, left and right and is struggling with the six senses which include the mind. The struggling jiva driven by kama and krodha worship different gods and aspire to acquire possessions within this world not knowing that the gods and this world are under Krishna. However, Krishna says to those miscreant jivas, I come as death. Krishna displays His universal form to prove His Supreme status of all the worlds and gods. Krishna says to Arjuna to not seek shelter within maya (this world) for Krishna says maya (world) is under "My" control and is "Mine". Krishna impels Arjuna to give up this materialism by fighting for Him - Krishna God of Gods.
The final super layer of thought enveloping all ideas is ananya bhakti (unalloyed devotional service). Krishna says if one can raise above the stages of the three modes, karma, and brahman one can reach the stage of ananya bhakti which Krishna says is the final refuge for the conditioned jiva. Because through ananya bhakti only, can one know Krishna in full truth. Other paths are progressive paths to this stage of ananya bhakti. Henceforth, Krishna urges Arjuna to bow down to Him in surrender and unconditional bhakti. This Krishna says is the most confidential of all truths spoken within the pages of Bhagavad Gita. By simply engaging in bhakti under the guidance of a spiritual master, Krishna says one can transcend this world of death and attain to His abode of eternality and bliss.
Summum BonumAfter saying all this, Krishna looks at Arjuna with compassion and says to him you may do as you like Arjuna! Arjuna with mind cleared up and doubts dispelled surrenders to the words of Krishna with a desire to execute the order of Krishna. Such willful surrender in devotion of the jiva to Krishna is the pinnacle of yoga and represents the summum bonum of this esoteric book called Bhagavad Gita.