There are different varieties of sacrifices according to the different class of men. The whole idea of Vedic literature is to give chance to every human being to develop spiritual consciousness under certain rules and regulations. So what is applicable to the persons who are in the modes of ignorance, they are not applicable to the persons who are in the modes of goodness, or those who are in the modes of passion, they are not applicable to the modes of goodness. The gradual process of evolution.
Lecture on Bhagavad-gita 4.24-34, New York, August 12, 1966