The fourth chapter is called "Jnana Karma Sanyasa Yoga" or "The application of Knowledge and Action to Yoga". Yoga is to be understood here as the first manifestation of Vedanta philosophy. Krishna, supreme deity of Yoga-Vedanta, tells Arjuna that He is born from age to age in this world; He is the Supreme Actor who is not tainted by action.
He asks Arjuna to perform all actions as a Yogi, in the spirit of sacrifice, for if man renounces au desire for the fruit of his actions he is unaffected by his acts and incurs no sin. Krishna recounts the variety of sacrifices that maybe performed in the name of God which are all born of action. Finally He tells Arjuna that Sacrifice of Knowledge is better than sacrifice of wealth.
The Blessed Lord said:
All this imperishable Yoga
Thus in succession handed down,
That very same and ancient Yoga
Much later was thy birth, O Lord,
The Blessed Lord said:
I have passed through many a birth,
Though of imperishable soul,
Whenever, O thou of Bharata race,
For the deliverance of the good,
My birth divine and actions, he
From fear, attachment, anger free,
Howsoever men come to me,
Those who success in actions seek,
The fourfold caste was made by me,
Nor me do actions ever taint,
Knowing this, men of old performed,
What action and inaction is
One has to know what action is,
In action who inaction sees,
Who hath his undertakings all
Renouncing all desire for fruit,
Devoid of hope, controlling mind,
Content with aught that he obtains,
Devoid of all attachment, free,
The oblation's Brahma, offering too,
There are some Yogis who perform
Some ears, and other senses too
All actions of the senses, some;
And some make sacrifice of wealth,
Some offer their incoming breath
Others who regulate their food,
The leavings of true sacrifice
Thus many a sacrifice is made
Better than sacrifice of wealth
Bending before thy master's feet,
Knowing this thou, O Pandava,
And even if thou art the most
As doth a blazing fire consume
There's nothing in this world indeed,
This knowledge gains the man of faith;
The ignorant one, devoid of faith,
Actions by Yoga who has renounced,
So with the sword of knowledge rend
Vivasvan: The first personal form of Vivasvat, the father of Manu.
Manu: Name of one of the great progenitors of the human race. He is said to be Man par excellence. The celebrated "Code of Manu" is ascribed to him.
Ikshavaku: A son of Manu.
Controlling Prakriti: God in Vedanta as well as Yoga is conceived as the ruler of Prakriti.
Maya: Maya is creative energy, and not an illusion as is commonly supposed. Here it is associated with God; sometimes it is associated with Prakriti too.
The four Castes, Gunas, and Action: This is the original idea of the Caste among the Hindus. A man belongs to a particular caste according to the actions he is required to perform.
Burning action in the fire of knowledge: According to Vedanta, or its first manifest form, Yoga, Knowledge and Action are but two counterparts of the same energy of Prana or self-conscious Breath. Burning actions in the fire of knowledge means, therefore, associating knowledge with action, and purifying it thereby.
Brahma and Sacrifice: Brahma is the supreme deity of Nyaya and Vaiseshika system, which hold that necessary actions must be performed as a Sacrifice. Here Krishna attempts to show that actions as a Sacrifice are enjoined in these systems too.
Ears and other senses: There are five senses of knowledge, ears, skin, eyes, tongue and the nose. Their respective attributes are sound, touch, sight, taste and smell. These are called the objects of the senses too.
Actions of the senses: Corresponding to the five senses of knowledge we have the five senses of action, feet, hands, tongue as organ of speech, the organ of creation, and the organ of excretion respectively. In these two verses we get the idea of the sacrifice or creative and selfless functions of the senses of knowledge and action.
Self-restraint: The idea of self-restraint is necessary to Sacrifice; for without it action becomes selfish and regardless of good to others.
Breath-control: Pranayama, by means of which we can control all functions of life. Control or restraint is essential in Sacrifice.
By sacrifice their sins consumed: There can be no effect of actions when they are performed as a Sacrifice. Hence Sacrifice consumes sin or the evil effects of actions.
Sacrifice made to Brahma: We have explained that Brahma is associated with the idea of Sacrifice.
Knowledge and Action: Here we are told that all actions culminate in knowledge, and vice versa. This is the point of view of Vedanta, which holds that knowledge and action are but two counterparts of the same energy of Prana or Breath.
Knowledge and Service: Here we see how knowledge may be acquired by acts of service or helpfulness, that is Sacrifice.
Knowledge consumes the sin of action: The two being harmonized, and action being performed as a Sacrifice, there can be no sin.