कुर्वेन्नेवेह कर्माणि जिजीविषेत शतं समाः
एवं त्वयि नान्यथेतोस्ति न कर्म लिप्यते नरे
The first mantra refers to jnana-nishtha, and is meant for those who have the ability to abandon all desires and establish themselves in knowledge alone. But on others who are not yet ready for such a state the performance of action in conformity with the natural inclination of the individual is enjoined: "By doing action alone here one should wish to live a hundred years. Thus it is in your case; there is no other way than this. Action dose not cling to man." One can wish to live as an individual only by performing actions. As long as there is the strong feeling that on is a human being alone, the laws pertaining to the human being have to be observed. One cannot live in one plane and observe the rules of another plane. The notion of one's being an individual is inseparably connected with the ideas of and the necessity for desire and action. The very fact of individuality denotes that individuality is not complete and one can never rest with peace in an incomplete condition. There is an involuntary urge from within to strive to become perfect. The individual, however, thinks that perfection consists in the acquisition of what is not already possessed. Moreover, the feeling of the need for certain external acquisitions is based on a special want felt within, though this want may change its nature from time to time. Every want manifests itself as an action and goads the body to move towards what is wanted. Even breathing and thinking are the implications of the necessity to exist as an individual ever striving in nature. There seems to be no other way of living as an individual than by the performance of action. If one refuses to perform action one shall be forced to perform action by the law of individual life. Instead of yielding to involuntary urges for action it is advisable to perform action consciously with good determinations, without a desire for selfish enjoyments, and with a knowledge of the law of action and reaction.
Shankara discusses the nature of action and knowledge and their relation between one another. Knowledge as Shankara understands it is not the knowledge that the human being is familiar with. The knowledge of the human being is knowledge of something other than the knower. It is always knowledge of some object or objects. It is divided knowledge that separates the object from the subject. It is incomplete knowledge, for, by it, it is not possible to know the subject and the object at one and the same time. When the one is known, the other is discarded and forgotten. It is not possible to have whole knowledge through a process, and perception or human knowledge is evidently a process. Process means change, and change is movement towards some thing or some state which marks the process as distinct from perfection. Hence, human knowledge is a perishable process of an ever non-enduring struggle for perfection. A struggle is not the same as an achievement, and truly speaking, human knowledge never achieves anything, substantially. The knowing faculty knows an object only as it wants to know it and as it is capable of knowing it, and not as the object is really in itself. The form and the nature of objects are determined by the form and the nature of the conceptual modifications of the faculty of knowing. Thus human knowledge is simply coating an existing object the true nature of which is never known. The knowledge of an individual is simply artificial. This is not the knowledge that Shankara is speaking of when he distinguishes it from action. Human knowledge is an action alone, because it is produced by the motion of the mind and the senses. The knowledge propounded in the Advaita Vedanta is objectless knowledge, and it is never produced but realised. It is not the knowledge of something but the knowledge of the knower himself. It is atma-sakshatkara that Shankara means by knowledge when he says that action is the antithesis of knowledge.