There are a few differing Buddhist views on sin. American Zen author Brad Warner states that in Buddhism there is no concept of sin at all. The Buddha Dharma Education Association also expressly states "The idea of sin or original sin has no place in Buddhism." Zen student and author Barbara O'Brien has said that "Buddhism has no concept of sin." Walpola Rahula also disagreed with the notion of sin, saying "In fact there is no 'sin' in Buddhism, as sin is understood in some religions." Ethnologist Christoph von Fürer-Haimendorf explained,