You must either believe he was who he said he was, or you must believe that he was a lunatic. That's what a believer will tell you. A believer of who, or what, you might ask? It doesn't really matter. The common perception of a person who makes supernatural claims is that the person is a lunatic, except of course for the followers of that person: they believe he really is what he says, and it often seems that he does too.
It starts in the wilderness, in a cave, or in a dungeon. A man is deprived of companionship, comforts, nutrition, sleep, and/or stimuli. He sees something that is as real as anything he has ever seen. He is not a lunatic, but his mind is strained to the point that it cannot govern itself. If the man is talented, intelligent, or influential, he may convince others to share the vision. It happens all the time.
It was in such dramatic circumstances, recalling the experience of Moses when face to face with the Burning Bush in the wilderness of Sinai, the successive visions of Zoroaster, the opening of the heavens and the descent of the Dove upon Christ in the Jordan, the cry of Gabriel heard by Muhammad in the Cave of Hira, and the dream of the Báb, in which the blood of the Imám Husayn touched and sanctified His lips, that Bahá'u'lláh, He "around Whom the Point of the Bayán hath revolved," and the Vehicle of the greatest Revelation the world has yet seen, received the first intimation of His sublime Mission, and that a ministry which, alike in its duration and fecundity, is unsurpassed in the religious history of mankind, was inaugurated. It was on that occasion that the "Most Great Spirit," as designated by Bahá'u'lláh Himself, revealed itself to Him, in the form of a "Maiden," and bade Him "lift up" His "voice between earth and heaven" --that same Spirit which, in the Zoroastrian, the Mosaic, the Christian, and Muhammadan Dispensations, had been respectively symbolized by the "Sacred Fire," the "Burning Bush," the "Dove," and the "Angel Gabriel."
- Shoghi Effendi, Messages to America, 1946.
But what Shoghi Effendi fails to mention is that such visions are not restricted to a few influential prophets; such hallucinations are an everyday occurance, and it doesn't just happen to lunatics!
Whatever their neurological and molecular antecedents, hallucinations feel real. They are sought out in many cultures, and considered a sign of spiritual enlightenment. Among the Native Americans of the Western Plains, for example, or many indigenous Siberian cultures, a young man's future was foreshadowed by the nature of the hallucination he experienced after a successful "vision quest"; its meaning was discussed with great seriousness among the elders and shamans of the tribe. There are countless instances in the world's religions where patriarchs, prophets, or saviors repair themselves to desert or mountain and, assisted by hunger and sensory deprivation, encounter gods or demons.
- Carl Sagan, The Demon-Haunted World, page 105.
The Siyah-Chal ("Black Pit"), into which Bahá'u'lláh was thrown, originally a reservoir of water for one of the public baths of Tihran, was a subterranean dungeon in which criminals of the worst type were wont to be confined. The darkness, the filth, and the character of the prisoners, combined to make of that pestilential dungeon the most abominable place to which human beings could be condemned. His feet were placed in stocks, and around His neck were fastened the Qara-Guhar chains, infamous throughout Persia for their galling weight. For three days and three nights, no manner of food or drink was given to Bahá'u'lláh. Rest and sleep were both impossible to Him. The place was infested with vermin, and the stench of that gloomy abode was enough to crush the very spirits of those who were condemned to suffer its horrors. Such were the conditions under which He was held down that even one of the executioners who were watching over Him was moved with pity. Several times this man attempted to induce Him to take some tea which he had managed to introduce into the dungeon under the cover of his garments. Bahá'u'lláh, however, would refuse to drink it. His family often endeavoured to persuade the guards to allow them to carry the food they had prepared for Him into His prison. Though at first no amount of pleading would induce the guards to relax the severity of their discipline, yet gradually they yielded to His friends' importunity. No one could be sure, however, whether that food would eventually reach Him, or whether He would consent to eat it whilst a number of His fellow-prisoners were starving before His eyes.
- Nabíl's Narrative, pp. 608-609