After he died, people followed `Abdu'l-Bahá. Bahá'u'lláh had written that `Abdu'l-Bahá had special powers, and that God would make sure that if `Abdu'l-Bahá explained anything that Bahá'u'lláh said, then the Bahá'ís should believe that explanation. `Abdu'l-Bahá also wrote a lot of letters and gave talks, and eventually visited Paris, London, Montreal, New York City, San Francisco and other cities in the west. This helped the Bahá'í Faith to spread in Europe and North America. He died in 1921. He left a will, where he told the Bahá'ís to follow his grandson, Shoghi Effendi.