Bhagavad Geeta: Chapter 2, Verses 29-38
Sri Krishna has been explaining the true nature of Self and how from the highest standpoint of Self, there is no need for Arjuna to grieve.
In the following verses, he comes down one level and explains from the material standpoint also that there is no need to grieve. The only way to live a life of merit is by doing his duty.
Chapter 2, Verse 29
Some see the Self as a wonder; some describe it as a wonder; some hear of the Self as a wonder; some having heard cannot understand it at all.
The description of the Self is so wonderful. Only those who can subtly go inward can see it as a wonder. The highest teaching of Vedanta is that you don’t have to find, realize or know the Self, you are the Self. This makes realizing Self extremely tough for those who are used to keeping their mind occupied. The utter ease of Self constitutes the utter difficulty of its realization.
The Self is only as far away from us as the waker is to the dreamer. When a mortal comes to experience the Self through the techniques of self-realization, the result is pure ecstasy and hence is described by them as wondrous. Some people may hear this and yet cannot understand it at all.
Chapter 2, Verse 30
O Arjuna, the Self that dwells within the body of everyone is immortal; therefore, you should not grieve for anyone.
If you sit near the ocean and grieves over the waves falling, you are going to be miserable. The waves inevitably exist and, the wave which rises will fall. But the ocean in which the waves rise, the waves fall and the waves exist is permanent.
The subtle indwelling spirit in every being is Eternal and indestructible. All that is destroyed is the container. The Self transcends the body and remains indestructible. Sri Krishna explains to Arjuna that hence there is no need to grieve.
Chapter 2, Verse 31
Besides, considering your duty as a warrior, you should not waver. For a Kshatriya (warrior), there is nothing higher than fighting for righteousness.
From this verse is explained the other delusion - the confusion in regards to duty. Sri Krishna says to Arjuna - For you, a warrior who is trained to protect the country, an opportunity has come to serve the nation. You will be most fulfilled if you are fighting this righteous war.
Every individual has a duty in nature. If everyone does their duty, society is peaceful. But if we escape it for selfish reasons, then problems come to society.
Chapter 2, Verse 32
O Partha (Arjuna), happy are the Kshatriyas (warriors) to whom such opportunities to fight in such a battle come unsought, as a wide-open door to heaven.
Kshatriya is not the name of the caste here. It's used to describe a person of a certain mental constitution, who is enthusiastic about defending the poor and weak from all threats of aggression.
Sri Krishna says to Arjuna - Without any effort, this war came to you. For the people who fight for a righteous war, for them, the doors are wide open to heaven. Only the blessed have the opportunity to lay down their life for the country.
Pandavas tried their level best for this war not to happen. But it is the arrogance of Kauravas that has caused this war to happen. Heroically when you fight the war firmly believing the righteousness, you will go to heaven. All heroic characters are happy and fulfilled when they get the opportunity to fight the war (without being the aggressors), even if they are sacrificing themselves to protect society.
Chapter 2, Verse 33
But, if you refuse to fight this righteous war, abandoning your duty and reputation, you will incur sin.
If you win, name, fame, etc., will come and, if you lose, then the doors of heaven will be open. But, if you don’t fight when you have to - in other words, if you give up your duty, for the welfare of the country (not for personal gain, for collective good), then for sure sin will incur. If you are not engaging yourself in the war, you are neglecting your duty. Action is negative or positive not because of the action but because of the motive behind it. Therefore, even from the standpoint of duty, you should not grieve.
Chapter 2, Verses 34, 35 and 36
People will recount your everlasting infamy (dishonor). For a respectable person who has been honored, infamy is worse than death.
The great generals who hold you in high esteem will think that you fled from the battle out of fear, and you will be looked down upon by those who respected your heroism in the past.
Your enemies will defame and humiliate you with unkind words, disregarding your might. What can be more painful than that?
You are such a well-known person. And everybody has you, Arjuna, in their heart. If you do not do your duty, everyone will endlessly take you as an example of how one should not be. For someone who is honored, this infamy of being remembered as one who doesn’t do his duty will be worse than death. You have tasted the joy of being valued, and appreciated, one action of yours is going to change the whole situation. Are you ready for it?
From the height of glory, you will fall into this abyss of infamy. Even your enemies who have honored you earlier will criticize you for your incapacity with words (low, vulgar) that I can’t even speak. No one is going to think about your sudden ahimsa bhāva. A warrior who gives up when the country needs him is going to be infamous and criticized endlessly. What can be more painful in life other than this?
Chapter 2, Verses 37 and 38
If you fight you will either be slain on the battlefield and go to heaven, or you will gain victory and enjoy the earth. Therefore, stand up with determination, O son of Kunti.
Treating alike happiness and distress, loss and gain, victory and defeat, engage in the battle for the sake of duty. Fulfilling your responsibility in this way, you will not incur sin.
There are only two options in the war, you win or lose. Either way, there is victory. So get up, and fight Arjuna. With a free mind do your duty.
If you are victorious, you have gained (for the country) and there will be joy. If you are defeated, you will have a loss and sorrow will be there. This is all part of existence. You should see both joy and sorrow, gain and loss, defeat and victory alike. When doing your duty, do it joyfully. Don’t be preoccupied with the results.
If you fight the war for selfish reasons or if you don’t do your duty, you will incur sin. If you do your duty as worship, for duty’s sake, there will be balance in joy and sorrow, balance in gain and loss, balance in victory and defeat. This will purify your heart and because of this purification of your mind, you will realize your true nature.
Intelligent action is called work. Not just sweating and laboring. Animals act, man alone can work. The glory of humans is that even though the instincts come up, we can think and judge them. If you determine that it is destructive to your peace and tranquility, or if you will cause restlessness to others then you shouldn't do it. Work is intelligent action. The architect, painter, and scientist are intelligently acting in the world and due to their capacity to work, life has been progressing among mankind.
From the next verse onwards Sri Krishna starts giving some techniques for self-perfection in the form of Karma yoga. It is foolish to think that life is one smooth ride, it is full of waves. We must learn how to ride the waves by being equanimous in physical, mental, and intellectual levels by performing our duty. This alone can inspire and bring success.