Anyone who has sampled even a few of the most commonly read Greek texts will have encountered pollution. The pollution of bloodshed is a frequent theme of tragedy: Orestes is driven mad; Oedipus brings plague upon all Thebes. In historical texts we find cities intervening in the internal affairs of others to 'drive out the pollution', or making war on account of it. Political orators represent their opponents as polluting demons. Purity is a constant concern in ritual texts, and any Greek underwent many small purifications in his everyday life. Certain abnormal religious movements of the archaic age made 'purification' the path to felicity in the afterlife. First published in hardback in 1983, Miasma is the first work in English to treat this theme in detail.