Variolation is the practice of introducing material from mild smallpox pustules into the skin of healthy people to induce a controlled infection and resulting immunity. There is evidence of its practice in India from at least the 11th century AD, possibly earlier, in the context of the cult of the goddess Śītalā. British physician Richard Holwell described in 1767 the procedure as practiced in Bengal: inoculators (tikādārs) collected material from mild pustule cases, preserved it in damp cloth, and introduced it via scarification into the patient's arm, with subsequent dietary and isolation instructions. The practice reached Europe via the Ottoman Empire: Lady Mary Wortley Montagu observed it in Istanbul in 1717 and introduced it to Britain in 1721. The transmission from India to Turkey and from Turkey to Europe was never formally acknowledged; Jenner's vaccination (1796) was presented as a radical innovation with no precedent, when it is in fact the scientific systematization of a non-European practice thousands of years old.