India's caste system can be seen as a codification of social classes found in any human society. Whether the late development of the jati system (wherein caste is determined by birth) along with related social injustice and abuse, should be attributed to Hindu religion or seen as a purely social phenomenon is a hot topic. Our scriptures have a clear answer. Listen now to the Vajrasuchi Upanishad, which, along with other ancient texts, states unambiguously: membership in the priestly brahmin, or brahmana, caste is determined by character, conduct and attainment, not by birth.
I shall describe the Vajrasuchi doctrine which blasts ignorance, condemns those who are devoid of the divine knowledge and exalts those endowed with the eye of knowledge.
The brahmana, the kshatriya, the vaishya and the sudra are the four castes. That the brahmana is the chief among these classes is in accord with the Vedic texts and is affirmed by the Smritis. Here there is a point worthy of investigation. Who is, verily, the brahmana? Is he the individual soul? Is he the body? Is he the class based on birth? Is he knowledge? Is he the deeds (previous, present or prospective)? Is he the performer of the rites?
To assume that the jiva, or the individual soul, is brahmana, it is not so, for the individual's form is one and the same in the large number of previous and prospective bodies. Even though the jiva is one, it assumes many bodies due to the stress of (past) karma, and in all these bodies the form of the jiva is one and the same. Therefore the jiva is not the brahmana.
If it is said that the body is the brahmana, it is not so, because of the sameness of the nature of the body which is composed of the five elements, in all classes of human beings down to the chandalas (outcastes), etc.; on account of the perception of the common features of old age and death, virtue and vice. Therefore the body is not the brahmana.
If it is said that birth makes the brahmana, it is not so, for there are many species among creatures, other than human, many sages are of diverse origin. We hear from the sacred books that Rsyasrnga was born of a deer, Kaushika of kusha grass, Jambuka from a jackal, Valmiki from an ant-hill, Vyasa from a fisher girl, Gautama from the back of a hare, Vasistha from Urvasi (the celestial nymph), Agastya from an earthen jar. Despite their birth, there are many sages who have taken the highest rank, having given proof of their wisdom. Therefore birth does not make a brahmana.
If it is said that knowledge makes a brahmana, it is not so, because among kshatriyas and others there are many who have seen the highest Reality and attained wisdom. Therefore knowledge does not make a brahmana.
Then if it is said that work makes a brahmana, it is not so, for we see that the work commenced in the present embodiment or accumulated during the previous or to commence on a future embodiment is common to all living creatures and that good men perform works impelled by their past karma. Therefore work does not make a brahmana.
Then if it is said that the performer of religious duties is a brahmana, it is not so, for there have been many kshatriyas and others who have given away gold–a religious duty. Therefore the performer of religious rites is not the brahmana.
Then who, verily, is the brahmana? He who, after directly perceiving, like the amalaka fruit in the palm of one's hand, the Self–without a second, devoid of distinctions of birth, attribute and action, devoid of all faults such as the six infirmities, and the six states, of the form of truth, wisdom, bliss and eternity, that is by itself, devoid of determinations, the basis of endless determinations, who functions as the indwelling spirit of all beings, who pervades the interior and the exterior of all, like ether, of the nature of bliss, indivisible, immeasurable, realisable only through one's experience and who manifests himself directly (as one's self)–and, through the fulfilment of his nature, becomes rid of the faults of desire, attachment, etc., and endowed with qualities of tranquillity, etc., rid of the states of being, spite, greed, expectation, bewilderment, etc., with his mind unaffected by ostentation, self-sense and the like, he lives. He alone, who is possessed of these qualities, is the brahmana. This is the view of the Vedic texts and tradition, ancient lore and history. The accomplishment of the state of the brahmana is otherwise impossible. Meditate on Brahman, the Self who is being, consciousness and bliss, without a second; meditate on Brahman, the Self who is being, consciousness and bliss without a second. This is the Upanishad.
Sama Veda, Vajrasucika Upanishad 1-9
Translated by Dr. S. Radhakrishnan