One final thing I have heard we should not have: The book attacking the Faith, by William Miller.
Dear Bahá'í Friend,
[Personal greetings deleted...] The House of Justice requests us to reply to your questions as follows.
It is apparent in letters written on behalf of the Guardian that he did not approve the publication of any photograph of Bahá'u'lláh, and regarded such publication to be offensive to religious feeling. Nor did he approve that the photograph be exposed openly to the public, even in Bahá'í homes. Only on special occasions did he permit the photograph to be displayed, and then he urged that it be done with the utmost reverence. The House of Justice, basing its comments on these instructions, has written a few letters to friends who have inquired about this subject and related matters, and for your guidance a compilation of extracts of these letters is enclosed.
With loving Bahá'í greetings,
For Department the Secretariat
"It would be good to advise the young Persian believer who has this
picture that, while we do not wish to suggest that he should remove the
photograph from his book, it would be inappropriate for him to show it to
others in a casual manner. As you know, the photograph of Bahá'u'lláh is
very precious and it should be handled with due reverence and respect."
(From a letter dated 7 February 1972 written by the Universal House of Justice to an individual believer)
"The portraits of the Bab and Bahá'u'lláh should be shown infrequently and on very special occasions, such as a special observance connected with an event intimately associated with the Forerunner or Founder of our Faith.
"We do not think that the regular National Convention is such a special
occasion, and we feel that the privilege of displaying these very precious
portraits should not be abused."
(From a letter dated 12 July 1973 written by the Universal House of Justice to the National Spiritual Assembly of Panama)