As stated in the Fifteenth Chapter, all the rules and regulations of the Vedas are meant for knowing Krsna. If one understands Krsna from the Bhagavad-gita and becomes situated in Krsna consciousness, engaging himself in devotional service, he has reached the highest perfection of knowledge offered by the Vedic literature. Lord Caitanya Mahaprabhu made this process very easy: He asked people simply to chant Hare Krsna, Hare Krsna, Krsna Krsna, Hare Hare/ Hare Rama, Hare Rama, Rama Rama, Hare Hare and to engage in the devotional service of the Lord and eat the remnants of foodstuff offered to the Deity. One who is directly engaged in all these devotional activities is to be understood as having studied all Vedic literature. He has come to the conclusion perfectly. Of course, for the ordinary persons who are not in Krsna consciousness or who are not engaged in devotional service, what is to be done and what is not to be done must be decided by the injunctions of the Vedas. One should act accordingly, without argument. That is called following the principles of sastra, or scripture. Sastra is without the four principal defects that are visible in the conditioned soul: imperfect senses, the propensity for cheating, certainty of committing mistakes, and certainty of being illusioned. These four principal defects in conditioned life disqualify one from putting forth rules and regulations. Therefore, the rules and regulations as described in the sastra-being above these defects-are accepted without alteration by all great saints, acaryas, and great souls.