3.14: All living bodies subsist on food grains; food grains are produced from rains, rains come from performance of sacrifice, and sacrifice is born of man's work.
15: Activity [karma] arises from the Vedas, and the Vedas spring from the Supreme Godhead. Therefore, the all-pervading Transcendence is eternally situated in acts of sacrifice.
YAJNARTHE KARMA, or the necessity for work for the satisfaction of Vishnu only, is more expressly stated in this verse. If we have to work for the satisfaction of the Yajna Purusa-Vishnu-then we must find the direction of work in Brahman, or the transcendental Vedas. The Vedas are therefore codes of working direction. Anything performed without the direction of the Vedas is called Vikarma, or unauthorized work, or sinful work. Therefore, one should always take direction from the Vedas to be saved from the reaction of work. As one has to work in ordinary life by the direction of the state, similarly, one has to work under direction of the supreme state of the Lord. Such instructions in the Vedas are directly manifested from the breathing of the Supreme Personality of Godhead. It is said: "All the four Vedas-namely Rigveda, Yajurveda, Samveda, and Atharvaveda-are emanations from the breathing of the great Personality of Godhead." The Lord, being potent, can speak by His breathing air, as is confirmed in The Brahma Samhita, for the Lord has the omnipotence to perform through each of his senses the actions of all other senses. In other words, the Lord can speak through His breathing, and He can impregnate by His eyes. It is said that He glanced over the material Nature and thus fathered all the living entities. So, after impregnating the conditioned soul into the womb of material Nature, He gave His direction in the Vedic wisdom as to how such conditioned souls can return home, back to Godhead. We should always remember that the conditioned souls in material Nature are all eager for material enjoyment. And the Vedic directions are so made that one can satisfy one's perverted desires, then return to Godhead, having finished this so-called enjoyment. It is a chance for the conditioned souls to attain liberation; therefore, the conditioned souls must try to follow the process of Yajna by becoming Krishna conscious. Those who have not followed the Vedic injunction may adopt the principles of Krishna consciousness, and that will take the place of performance of Vedic Yajnas, or karma.