An underground spring in Nazareth traditionally served as the city’s main water source for several centuries, possibly millennia; however, it was not always referred to as "Mary's well" or "Mary's spring". In his book, "The Bible as History", Werner Keller writes that "Mary's Well" or "Ain Maryam", as the locals called it, had been so named since "time immemorial" and that it provided the only water supply in the area. William Rae Wilson also describes "a well of the Virgin, which supplied the inhabitants of Nazareth with water" in his book, "Travels in Egypt and the Holy Land" (1824).