July 7

A comparison of their contents [the Will and Testament of ‘Abdu’l-Bahá with the Kitáb-i-Aqdas] with the rest of Bahá’í sacred Writings will similarly establish the conformity of whatever they contain with the spirit as well as the letter of the authenticated writings and sayings of Bahá’u’lláh and ‘Abdu’l-Bahá. In fact, he who reads the Aqdas with care and diligence will not find it hard to discover that the Most Holy Book itself anticipates in a number of passages the institutions which ‘Abdu’l-Bahá ordains in His Will. By leaving certain matters unspecified and unregulated in His Book of Laws, Bahá’u’lláh seems to have deliberately left a gap in the general scheme of Bahá’í Dispensation, which the unequivocal provisions of the Master’s Will have filled. 
(Shoghi Effendi, from a letter dated February 27, 1929; ‘The World Order of Baha’u’llah’)