Sacred contagion is the belief that spiritual properties within an object, place, or person may be passed to another object, place, or person, usually by direct contact or physical proximity.
While the concept of sacred contagion has existed in numerous cultures since before recorded history, the term "sacred contagion" originated with French sociologist Émile Durkheim, who introduced it in his book, The Elementary Forms of Religious Life.
The text also gives many examples of sacred contagion brought about by contact with these spiritually unclean people and things.
Anthropologist Mary Douglas, whose work is heavily influenced by Durkheim, wrote an extensive modern work on the topic of sacred contagion entitled Purity and Danger: An Analysis of the Concepts of Pollution and Taboo.
Douglas and Durkheim both rejected the idea that concepts of purity and impurity, such as those found in Leviticus, were an attempt to use religion to explain hygiene, an otherwise impossible task in the scientific terms of the time, several millennium before the concept of germs.