Ablution refers to the procedures of ritual washing undertaken to counteract a state of impurity and to reinstate purity. 1. Situations requiring ablution In the Islamic system of ritual purity (ṭahāra), Muslims can become ceremonially "polluted" or "precluded" in two primary ways: (1) by coming into and remaining in contact with a set of substances or organisms possessing a status known (by relatively late authorities) as najāsa ḥissiyya/ḥaqīqiyya or "tangible impurity," for example: urine, feces, blood, semen, pigs, dogs, carrion, wine, pre-ejaculatory fluid, a "marred egg" (i.e.,