Omniscience at will

Any claim to omniscience is likely to come up for a serious challenge in our time, in our world. There is so much to know already, and more every moment. In explaining the difference between the infallibility, the divine protection of the Guardian from that characterizing the Manifestation of God, the Guardian directed his secretary to write the following in a letter dated 4 March 1948 to an individual believer in the British Isles:

He likes to be provided with facts by the friends, when they ask his advice, for although his decisions are guided by God, he is not, like the Prophet, omniscient at will, in spite of the fact that he often senses a situation or condition without having any detailed knowledge of it....
(Shoghi Effendi, The Unfolding Destiny of the British Baha'i Community, p. 448; cited in Lights of Guidance, p. 310)

Two letters written on behalf of the Universal House of Justice by its Secretariat have indicated that, like the Guardian, the Universal House of Justice is likewise not omniscient:

However, the Universal House of Justice is not omniscient; like the Guardian, it wants to be provided with facts when called upon to render a decision, and like him it may well change its decision when new facts emerge. (From a letter written to an individual believer dated 22 August 1977; in Lights of Guidance, p. 311)

However, the Universal House of Justice is not omniscient, and the friends should understand that there is a difference between infallibility and omniscience. (From a letter written to an individual believer dated 14 June 1996; in Ocean)

We return again to the assertion that the "Prophet" is "omniscient at will". Do we find the Baha'u'llah claiming omniscience for Himself? Consider the following passage from the Suratu'l-Haykal, a passage of which (quoted in The World Order of Baha'u'llah, p. 109 and bolded below) was translated by Shoghi Effendi:

O Temple of Holiness! We, verily, have made Thine inmost heart the treasury of all the knowledge of past and future ages, and the dawning-place of Our own knowledge which We have ordained for the dwellers of earth and heaven, that all creation may partake of the outpourings of Thy grace and may attain, through the wonders of Thy knowledge, unto the recognition of God, the Exalted, the Powerful, the Great. In truth, that knowledge which belongeth unto Mine own Essence is such as none hath ever attained or will ever grasp, nor shall any heart be capable of bearing its weight. Were We to disclose but a single word of this knowledge, the hearts of all men would be filled with consternation, the foundations of all things would crumble into ruin, and the feet of even the wisest among men would be made to slip.

Within the treasury of Our Wisdom there lieth unrevealed a knowledge, one word of which, if we chose to divulge it to mankind, would cause every human being to recognize the Manifestation of God and to acknowledge His omniscience, would enable every one to discover the secrets of all the sciences, and to attain so high a station as to find himself wholly independent of all past and future learning. Other knowledges We do as well possess, not a single letter of which We can disclose, nor do We find humanity able to hear even the barest reference to their meaning. Thus have We informed you of the knowledge of God, the All-Knowing, the All-Wise. Were We to find worthy vessels, We would deposit within them the treasures of hidden meanings and impart unto them a knowledge, one letter of which would encompass all created things.

O Inmost Heart of this Temple! We have made thee the dawning-place of Our knowledge and the dayspring of Our wisdom unto all who are in heaven and on earth. From thee have We caused all sciences to appear, and unto thee shall We cause them to return. And from thee shall We bring them forth a second time. Such, indeed, is Our promise, and potent are We to effect Our purpose. Erelong shall We bring into being through thee exponents of new and wondrous sciences, of potent and effective crafts, and shall make manifest through them that which the heart of none of Our servants hath yet conceived. Thus do We bestow upon whom We will whatsoever We desire, and thus do We withdraw from whom We will what We had once bestowed. Even so do We ordain whatsoever We please through Our behest.
(Baha'u'llah, Suratu'l-Haykal, in The Summons of the Lord of Hosts, pp. 34-36)

Shoghi Effendi often cited the exact words of Baha'u'llah, presenting them to the believers so that they can read His words for themselves. Rather than giving his own paraphrase or explanation, he cited what Baha'u'llah wrote and left it at that. However this does not indicate that he did not refer to the omniscience of the Manifestation, albeit obliquely. In one of His Tablets, 'Abdu'l-Baha writes on the topic of the accuracy of various historical accounts:

Our purpose is to show that even in Scriptural history, the most outstanding of all histories, there are contradictions as to the time when the great ones lived, let alone as to the dates related to others. And furthermore, learned societies in europe are continually revising the existing records, both of East and West. In spite of this, how can the confused accounts of peoples dating from before Alexander be compared with the Holy Text of God? If any scholar expresses astonishment, let him be surprised at the discrepancies in Scriptural history.
Nevertheless, Holy Writ is authoritative, and with it no history of the world can compare, for experience hath shown that after investigation of the facts and a thorough study of ancient records and corroborative evidence, all establish the validity of God's universal Manifestation; once His claim proveth true, then whatsoever He may choose to say is right and correct.
(From the authorized translation of an unpublished Tablet of 'Abdu'l-Bahá to Ethel Rosenberg in 1906 in reply to her questions about the Tablet of Wisdom. Research Department, Bahá'í World Centre. Published pp 78-81 in Ethel Jenner Rosenberg, the Life and Times of England's Outstanding Bahá'í Pioneer Worker, by Robert Weinberg (George Ronald, Oxford, 1995).

In two letters written by his secretaries on his behalf, the Guardian affirmed his confidence in the judgment of 'Abdu'l-Baha with regard to historical events:

As regards what Mirza Abu'l-Fadl has said concerning the seven religions of the past, Shoghi Effendi wishes to emphasize that what are truly authoritative are the Master's words. In all such cases we should try and find out what He has said, and abide by His words, even though they seem conflicting with the findings of modern scholars.
(From a letter to Shahnaz Waite dated 23 February 1933; in United States Baha'i News, No. 77, September 1933, pp. 1-2; cited in compilations dated 14 September 1987 and 31 January 1995 issued by the Baha'i World Center)

Historians cannot be sure Socrates did not visit the Holy Land. But believing as we do that 'Abdu'l-Bahá had an intuitive knowledge quite different from our own, we accept His authority on this matter.... (From a letter written to an individual believer dated 7 June 1946; in Arohanui - Letters to New Zealand, p. 88)

In view of these references to the authority of the Manifestation with regard to historical events as indicated by 'Abdu'l-Baha, and the infallibility of the Master in the interpretation of the Baha'i texts and teachings, and finally the infallibility of the Guardian in the interpretation of those same Baha'i texts and teachings, it can be affirmed with confidence that the omniscience claimed by Baha'u'llah in the Suratu'l-Haykal is reiterated by His chosen and authoritative expounders. As such it appears to be a Baha'i doctrine of unquestionable authority and truth.