Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 4
Sanskrit:
कालेन स्नानशौचाभ्यां संस्कारैस्तपसेज्यया ।शुध्यन्ति दानै: सन्तुष्टया द्रव्याण्यात्मात्मविद्यया ॥ ४ ॥
ITRANS:
kālena snāna-śaucābhyāṁsaṁskārais tapasejyayāśudhyanti dānaiḥ santuṣṭyādravyāṇy ātmātma-vidyayā
Translation:
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.
Purport:
These are śāstric injunctions concerning how one can purify everything according to Vedic civilization. Unless purified, anything we use will infect us with contamination. In India five thousand years ago, even in the villages such as that of Nanda Mahārāja, people knew know to purify things, and thus they enjoyed even material life without contamination.