In many places in Bhagavad-gita, the Supreme Lord, Krsna, refers to the varnasrama-dharma of four varnas and four asramas. He teaches people about this varnasrama-dharma so that all of human society can live peacefully by observing the principles for the four social divisions and four spiritual divisions (varna and asrama) and thus make advancement in spiritual knowledge. The Manus compiled the Manu-samhita. The word samhita means Vedic knowledge, and manu indicates that this knowledge is given by Manu. The Manus are sometimes incarnations of the Supreme Lord and sometimes empowered living entities. Formerly, many long years ago, Lord Krsna instructed the sun-god. The Manus are generally sons of the sun-god. Therefore, while speaking to Arjuna about the importance of Bhagavad-gita, Krsna said, imam vivasvate yogam proktavan aham avyayam vivasvan manave praha: [Bg. 4.1] This instruction was given to Vivasvan, the sun-god, who in turn instructed his son Manu. Manu gave the law known as Manu-samhita, which is full of directions based on varna and asrama concerning how to live as a human being. These are very scientific ways of life, but under the rule of demons like Hiranyakasipu, human society breaks all these systems of law and order and gradually becomes lower and lower. Thus there is no peace in the world. The conclusion is that if we want real peace and order in the human society, we must follow the principles laid down by the Manu-samhita and confirmed by the Supreme Personality of Godhead, Krsna.