Ritual purity and impurity
Many religions teach that some substances, often types of food, body fluids or certain animals, are impure and somehow pollute the individual who has contact with them. Usually related to such ideas and following from them is the notion that washing in water will restore the individual to a state of purity.
Such beliefs were prevalent in India at the time of the Buddha. Hinduism taught that sins could be washed away by bathing in the Ganges or other sacred rivers (M.I,39). It also taught that contact with people of lower caste, with menstruating women or with certain animals like dogs would pollute them. As with other similar beliefs and superstitions, the Buddha subjected the notion of ritual impurity to reason and found it wanting. Contact with dirt, he said, may well make one dirty but this could simply be remedied by washing (M.II,151).
When told that people could wash away their sins by bathing in sacred rivers, the nun Puõõikà quipped that if this were so then all the turtles, crocodiles and frogs would go to heaven (Thi.341). Real pollution, the Buddha maintained, came from negative thoughts and immoral behaviour and this could only be ‘cleaned’ by changing one’s heart and one’s actions. In the Majjhima Nikaya (M.I,39) he called this the ‘inner washing’ (sinàto antarena sinànenàti).