SB 10.5.4

kālena snāna-śaucābhyāṁ
 saṁskārais tapasejyayā
śudhyanti dānaiḥ santuṣṭyā
 dravyāṇy ātmātma-vidyayā
Synonyms: 
kālena — by due course of time (the land and other material things become purified); snāna-śaucābhyām — by bathing (the body becomes purified) and by cleansing (unclean things become purified); saṁskāraiḥ — by purificatory processes (birth becomes purified); tapasā — by austerity (the senses become purified); ijyayā — by worship (the brāhmaṇas become purified); śudhyanti — become purified; dānaiḥ — by charity (wealth becomes purified); santuṣṭyā — by satisfaction (the mind becomes purified); dravyāṇi — all material possessions, such as cows, land and gold; ātmā — the soul (becomes purified); ātma-vidyayā — by self-realization.
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.