SB 10.5.4

O King, by the passing of time, land and other material possessions are purified; by bathing, the body is purified; and by being cleansed, unclean things are purified. By purificatory ceremonies, birth is purified; by austerity, the senses are purified; and by worship and charity offered to the brāhmaṇas, material possessions are purified. By satisfaction, the mind is purified; and by self-realization, or Kṛṣṇa consciousness, the soul is purified. KB 10.5.4 In the material world we possess riches and wealth in many ways, but sometimes not in very honest and pious ways, because that is the nature of accumulating wealth. According to Vedic injunction, therefore, one should purify such wealth by giving cows and gold in charity to the brāhmaṇas. A newborn child is also purified by gifts of grain in charity to the brāhmaṇas. In this material world it is to be understood that we are always living in a contaminated state. We therefore have to purify the duration of our lives, our possession of wealth and our self. We can purify our duration of life by taking daily bath and cleansing the body inside and outside and accepting the ten kinds of purificatory processes. By austerities, by worship of the Lord, and by distribution of charity we can purify the possession of wealth. We can purify our self by studying the Vedas in order to understand the Absolute Truth and achieve self-realization. It is therefore stated in the Vedic literature that by birth everyone is born a śūdra, that by accepting the purificatory process one becomes twice-born, that by studying the Vedas one becomes a vipra, which is the preliminary qualification for becoming a brāhmaṇa, and that when one perfectly understands the Absolute Truth he is called a brāhmaṇa. And when the brāhmaṇa reaches further perfection, he becomes a Vaiṣṇava, or a devotee.