The ancient Indian tradition of social hierarchy is deeply rooted in the caste system. Based on this system, the society is divided into four classes, which are the Brahman, the Ruler (khattiya), the Trader (vessa), and the Servant (sudda). At the top of the hierarchy is the Brahman class who enjoys the highest status and privileges, then followed by the Ruler, the Trader, and the Servant at the bottom. The Indian caste system is based on birth and lineage, which will determine one’s social position and one’s profession in society. Individuals inherit their caste from their parents and pass them down to their children. This means that no matter what people do, they cannot change their caste. The lower castes will always be bounded by the social limitation. The Buddha strongly rejects the caste system and the social inequality within the classes. In Dhammapada and “The Origin of Things”, the Buddha further emphasizes his rejection by explaining that birth should not be the determinant of one’s social rank, the equality within classes, and the Truth is the best thing in the world.
In chapter XXVI of Dhammapada, the Buddha elaborates on how one can become a brāhmaṇa. Here brāhmaṇa refers to arhat, not the social class. The Buddha says that (Dhammapada, 67):
Not by matted hair, nor by clan,
Nor by birth does one become a brāhmaṇa.
In whom is truth and dhamma,
He is the pure one, and he is the brāhmaṇa. (393)

And I do not call one a brāhmaṇa
Merely by being born from a [brāhmaṇa] womb,
Sprung from a [brāhmaṇa] mother.
He is merely a ‘bho-sayer’ (396)
Here the Buddha clearly states that birth and family are not factors for one to become a brāhmaṇa (arhat). Tradionally, the brahmans are priests or monks. However, the Buddha explains that being born in the Brahman class does not necessarily make someone an enlightened monk or arhat. The only way to become an arhat is by following and practicing the Buddha’s dhamma. This shows that the Buddha puts less emphasis on birth and caste system.
Moreover, in “The Origins of Things” the Buddha strengthens his rejection toward the caste system by placing a higher value on the equality of the people and morality. He says, “… bad and good qualities, which are condemned and praised by the wise, are both found distributed among these four classes,” (Sayings, 119). There are evil people as well as virtuous people in every caste. This means that all classes are equally capable to create both good and bad karma. The Buddha also explains that the states of rebirth are determined by one’s karma and one’s view at the time of death, regardless their classes (Sayings, 127). This once again emphasis the equality of people that anyone regardless his class can be reborn to a fortunate condition if he has wholesome thoughts and right view at the time of the death, while people who have either unwholesome thoughts or mistaken view at the time of death will be born in unfortunate condition. This equality certainly rebuts the traditional idea that the Brahman should be best class rank in the ancient Indian traditional social hierarchy.
Finally, the Buddha explains in the “Origins of Things”, “…Truth is the best in the world, both here and now and for the future,” (Sayings, 119). The best thing to be in the world is to attain enlightenment and get out from the cycle of samara. The only way to attain nirvana is by acknowledging the Four Noble Truth, following the Eightfold Path, and detaching from the Five Aggregates. Here the Buddha states that people regardless of their classes can attain nirvana because the most important factor is not the social rank or birth, but the Truth. This supports Buddha’s rejection to the raditional social hierarchy by showing that social caste is irrelevant to attain enlightenment.
Therefore, it is clear that the Buddha rejects the ancient Indian traditional social hierarchy. The Buddha strongly criticizes the inequality in the caste system. According to the Dhammapada, birth should have nothing to do with one’s quality of life. Being born as a priest does not make one an enlightened being. In “The Origins of Things”, the Buddha also explains that all classes are equal. People, regardless their classes, have equal chances to create good karma and attain nirvana as long as they follow the Truth. The best thing in the world is not to be born in the highest class, but to become one who attains enlightenment by following the Buddha’s dhamma.