1932 - One must Deepen his Knowledge of the Literature in Order to Teach Others and Render Service to the Faith
" .... Shoghi Effendi hopes that you will exert all your effort to deepen your knowledge of the literature of the movement, until you become fully acquainted with its spirit and tenets. Unless you do obtain such a firm hold you will never be able to teach others and render real service to the promulgation of the Faith. Of special importance is the Book of the Íqán which explains the attitude of the Cause towards the prophets of God and their mission in the history of society. Besides this there is Some Answered Questions of the Master and the 'Dawn-Breakers' of Nabil. Every Bahá'í should master these books and be able to explain their contents to others. Besides their importance, they are interesting and most absorbing."
(From a letter written on behalf of Shoghi Effendi to an individual believer, February 9, 1932) (Compilations, Lights of Guidance, p. 568)
1937 - Creatures are to be Found on Every Planet
"Regarding the passage on p. 163 of the 'Gleanings'; the creatures which Bahá'u'lláh states to be found in every planet cannot be considered to be necessarily similar or different from human beings on this earth. Bahá'u'lláh does not specifically state whether such creatures are like or unlike us. He simply refers to the fact that there are creatures in every planet. It remains for science to discover one day the exact nature of these creatures."
(From a letter written on behalf of Shoghi Effendi to an individual believer, February 9, 1937) (Compilations, Lights of Guidance, p. 478)
1989 - Bahá'í institutions… placing too much reliance on large, expensive projects
The International Teaching Centre has concluded that the Bahá'í institutions in ... seem to have been placing too much reliance on large, expensive projects, involving a great deal of successful public relations and proclamation. These are, in their own way, very useful activities, but it must be realized that they cannot be expected to produce large numbers of new believers. The key to the conversion of people to the Faith is the action of the individual Bahá'í conveying the spark of faith to individual seekers, answering their questions and deepening their understanding of the teachings.
(9 February 1989, written on behalf of the Universal House of Justice to a National Spiritual Assembly)  (The Universal House of Justice, 1993 Nov 09, Promoting Entry by Troops, p. 15)