evam pravartitam cakram
mogham partha sa jivati
My dear Arjuna, one who does not follow in human life the cycle of sacrifice thus established by the Vedas certainly leads a life full of sin. Living only for the satisfaction of the senses, such a person lives in vain.
Commentary by Srila Prabhupada
The mammonist philosophy of “work very hard and enjoy sense gratification” is condemned herein by the Lord. Therefore, for those who want to enjoy this material world, the above-mentioned cycle of performing yajnas is absolutely necessary. One who does not follow such regulations is living a very risky life, being condemned more and more. By nature’s law, this human form of life is specifically meant for self-realization, in either of the three ways—namely karma-yoga, jnana-yoga, or bhakti-yoga. There is no necessity of rigidly following the performances of the prescribed yajnas for the transcendentalists who are above vice and virtue; but those who are engaged in sense gratification require purification by the above mentioned cycle of yajna performances. There are different kinds of activities. Those who are not Krishna conscious are certainly engaged in sensory consciousness; therefore they need to execute pious work. The yajna system is planned in such a way that sensory conscious persons may satisfy their desires without becoming entangled in the reaction of sense-gratificatory work. The prosperity of the world depends not on our own efforts but on the background arrangement of the Supreme Lord, directly carried out by the demigods. Therefore, the yajnas are directly aimed at the particular demigods mentioned in the Vedas. Indirectly, it is the practice of Krishna consciousness, because when one masters the performance of yajnas one is sure to become Krishna conscious. But if by performing yajnas one does not become Krishna conscious, such principles are counted as only moral codes. One should not, therefore, limit his progress only to the point of moral codes, but should transcend them, to attain Krishna consciousness.
Commentary by Sri Visvanatha Cakravarti Thakur
This verse speaks of the sin involved in not performing the sacrifice. He who does not partake in the instituted cycle moving from beginning to end—from yajna to rain; from rain to food; from food to nourishment of men; from men to performance of yajna; from yajna to rain—with performance of yajna—leads a life full of sin. Who will not sink to hell?
Foot Note: The cycle is as follows: Supreme Lord, Vedas, action, sacrifice, rain, food, and production of living entities. The new living entities then study the Vedas arising from the Lord, perform action, and sacrifice (with the Lord present within) again. At the same time as fulfilling ones material needs by sacrifice one can attain the Lord. Ramanuja takes brahman as the body and aksara as the soul, which is necessary for the body to function. Then the cycle is: soul in the body, action, sacrifice, rain, food, nourishment of the body with a soul bhutani); then action, sacrifice etc. Madhva takes brahman as the Lord and aksara as the Vedas. Vedas reveal the Lord, the Lord inspires prescribed action, then sacrifice, rain, food, nourishment of bodies, study of Vedas, revelation of the Lord, inspiration to action etc.