Sacred cow
An English idiom for an idea or institution held to be beyond criticism, drawn from the Hindu reverence for the cow.
Also: sacred cows
In English a sacred cow is something treated as beyond question, such as a long-held policy, a tradition or a revered figure, as in the phrase to kill a sacred cow. The idiom grew up in American English in the early twentieth century from outsiders' impressions of the Hindu respect for cows in India, where cattle may wander freely through busy streets. In anthropology, Marvin Harris's 1966 essay on the cultural ecology of India's sacred cattle argued that reverence for the cow made practical sense in a farming economy built on bullocks, dung and milk, an argument that has been widely debated since.