In many places in Bhagavad-gītā, the Supreme Lord, Kṛṣṇa, refers to the varṇāśrama-dharma of four varṇas and four āśramas. He teaches people about this varṇāśrama-dharma so that all of human society can live peacefully by observing the principles for the four social divisions and four spiritual divisions ( varṇa and āśrama ) and thus make advancement in spiritual knowledge. The Manus compiled the Manu-saṁhitā. The word saṁhitā 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 Kṛṣṇa instructed the sun-god. The Manus are generally sons of the sun-god. Therefore, while speaking to Arjuna about the importance of Bhagavad-gītā, Kṛṣṇa said, imaṁ vivasvate yogaṁ proktavān aham avyayam vivasvān manave prāha: “This instruction was given to Vivasvān, the sun-god, who in turn instructed his son Manu.” Manu gave the law known as Manu-saṁhitā, which is full of directions based on varṇa and āśrama concerning how to live as a human being. These are very scientific ways of life, but under the rule of demons like Hiraṇyakaśipu, 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-saṁhitā and confirmed by the Supreme Personality of Godhead, Kṛṣṇa.