Essence of Gita -1

Gita rests upon two pillars - of sacrifice and renunciation. As stated by Sri Ramakrishna, Gita is the word Tagi (or Tyagi - one who has renounced - according to Sanskrit grammer both the words are same) repeated 10 times. 

The word sacrifice is of great significance. It first appears as the word "Yajna" in the 3rd Chapter - Yoga of Action. According to Gita, every action in this world can be construed as a sacrifice and an action devoid of the spirit of sacrifice is no action at all - it is vikarma or adverse action. The 3rd chapter talks about the procreation and the ecological cycle as a grand sacrifice and also proclaims that the ideal action is one which is done in the selfless spirit of sacrifice as that does not cause any bondage. Action driven by impulses of anger and desire are born out of ignorance and thereby cause bondage, but inaction is not a way to gain knowledge for those who have not renounced action and are still ignorant of the Self. In 4th Chapter this is explained in a more lucid style. Sacrifices are various in nature, in fact, all actions should be done in a spirit of sacrifice, that is the right spirit. That spirit of action will render one free, not inaction. Of all the sacrifices (that are sprung of action) the sacrifice in the form of true knowledge or wisdom (of Self) is the greatest and grandest sacrifice. There is nothing holier than true knowledge. All form of selfless sacrifices lead one to the path of renunciation. The true knowledge is one in which one is able to completely forget self, i.e. forego ego and realize the Atman - the all encompassing spirit that pervades everything.

The fifth chapter further builds on the concept of renunciation and asserts that the path of renunciation and path of selfless action are essentially the same, because the goals are same. Therefore Gita is the first scripture which harmonizes different paths, different opinions and different tendencies - "Ye yatha mam prapadyante tansthathaiva bhajami aham" - Whomsover worships Me through whichever path, I reach out to him. A true renunciation means absolute detachment, like lotus leaf on water, which never gets under water, always floats above it. Likewise true renunciation means performing an action in an absolute spirit of detachment - not desiring its fruits and even considering the essential daily functions as mere functions of the body. This is because the Supreme spirit, who is the eternal consciousness is beyond all actions. True renunciation means going beyond all pairs of opposites and seeing the eternal and everlasting spirit in everything, thereby treating every being as equal (the spirit manifested).