In the 18th century, Europeans began an experiment known as "inoculation or variolation" to prevent, not cure the smallpox. Lady Mary Wortley Montagu defied convention, most memorably by introducing smallpox inoculation to Western medicine after witnessing it during her travels and stay in the Ottoman Empire. Previously, Lady Mary's brother had died of smallpox in 1713, and although Lady Mary recovered from the disease in 1715, it left her with a disfigured face. In the Ottoman Empire, she visited the women in their segregated zenanas, a house for Muslims and Hindus, making friends and learning about Turkish customs. There in March 1717, she witnessed the practice of inoculation against smallpox – variolation – which she called engrafting, and wrote home about it in a number of her letters. The most famous of these letters was her "Letter to a Friend" of 1 April 1717. Variolation used live smallpox virus in the pus taken from a mild smallpox blister and introduced it into scratched skin of the arm or leg (the most usual spots) of a previously uninfected person to promote immunity to the disease. Consequently, the inoculate would develop a milder case of smallpox than the one he/she might have contracted.