One should act to satisfy the Supreme Lord. For example, Arjuna was a ksatriya. He was hesitating to fight the other party. But if such fighting is performed for the sake of Krsna, the Supreme Personality of Godhead, there need be no fear of degradation. In the business field also, sometimes a merchant has to tell so many lies to make a profit. If he does not do so, there can be no profit. Sometimes a merchant says, "Oh, my dear customer, for you I am making no profit," but one should know that without profit the merchant cannot exist. Therefore it should be taken as a simple lie if a merchant says that he is not making a profit. But the merchant should not think that because he is engaged in an occupation in which the telling of lies is compulsory, he should give up his profession and pursue the profession of a brahmana. That is not recommended. Whether one is a ksatriya, a vaisya, or a sudra doesn't matter, if he serves, by his work, the Supreme Personality of Godhead. Even brahmanas, who perform different types of sacrifice, sometimes must kill animals because sometimes animals are sacrificed in such ceremonies. Similarly, if a ksatriya engaged in his own occupation kills an enemy, there is no sin incurred. In the Third Chapter these matters have been clearly and elaborately explained; every man should work for the purpose of yajna, or for Visnu, the Supreme Personality of Godhead. Anything done for personal sense gratification is a cause of bondage. The conclusion is that everyone should be engaged according to the particular mode of nature he has acquired, and he should decide to work only to serve the supreme cause of the Supreme Lord.