`Abdu'l-Bahá, the son of the founder of the religion, wrote a series of letters, or tablets, to the followers of the religion in the United States in 1916-1917; these letters were compiled together in the book titled Tablets of the Divine Plan.
Shoghi Effendi, head of the religion after the death of `Abdu'l-Bahá in 1921, wrote a cable on 1 May 1936 to the Bahá'í Annual Convention of the United States and Canada, and asked for the systematic implementation of `Abdu'l-Bahá's vision to begin [REF].