In 1852, Baha’u’llah was wrongfully imprisoned in the Siyah-Chal dungeon (The Black Pit), in Tehran, for 4 months (This began 40 years of exile and imprisonment). It was in the Siyah-Chal that He received the Holy Spirit. Just as the Holy Spirit was received by Moses at the Burning Bush, Krishna in the War Chariot of Arjuna, Buddha beneath the Bo Tree, Zoroaster at the Setting Sun, Jesus in the River Jordan in the form of a dove descending, and Muhammad in the Cave of Hira, so also Baha’u’llah received the Holy Spirit in the Siyah-Chal in the form of the Maiden of Heaven appearing to Him:
We were consigned for four months to a place foul beyond comparison. As to the dungeon in which this Wronged One and others similarly wronged were confined, a dark and narrow pit were preferable. Upon Our arrival We were first conducted along a pitch-black corridor, from whence We descended three steep flights of stairs to the place of confinement assigned to Us. The dungeon was wrapped in thick darkness, and Our fellow prisoners numbered nearly a hundred and fifty souls: thieves, assassins and highwaymen. Though crowded, it had no other outlet than the passage by which We entered. No pen can depict that place, nor any tongue describe its loathsome smell. Most of these men had neither clothes nor bedding to lie on. God alone knoweth what befell Us in that most foul-smelling and gloomy place!
One night, in a dream, these exalted words were heard on every side: “Verily, We shall render Thee victorious by Thyself and by Thy Pen. Grieve Thou not for that which hath befallen Thee, neither be Thou afraid, for Thou art in safety. Erelong will God raise up the treasures of the earth — men who will aid Thee through Thyself and through Thy Name, wherewith God hath revived the hearts of such as have recognized Him.” 
While engulfed in tribulations I heard a most wondrous, a most sweet voice, calling above My head. Turning My face, I beheld a Maiden — the embodiment of the remembrance of the name of My Lord — suspended in the air before Me. So rejoiced was she in her very soul that her countenance shone with the ornament of the good pleasure of God, and her cheeks glowed with the brightness of the All-Merciful. Betwixt earth and heaven she was raising a call which captivated the hearts and minds of men. She was imparting to both My inward and outer being tidings which rejoiced My soul, and the souls of God’s honoured servants.
Pointing with her finger unto My head, she addressed all who are in heaven and all who are on earth, saying: By God! This is the Best-Beloved of the worlds, and yet ye comprehend not. This is the Beauty of God amongst you, and the power of His sovereignty within you, could ye but understand. This is the Mystery of God and His Treasure, the Cause of God and His glory unto all who are in the kingdoms of Revelation and of creation, if ye be of them that perceive. This is He Whose Presence is the ardent desire of the denizens of the Realm of eternity, and of them that dwell within the Tabernacle of glory, and yet from His Beauty do ye turn aside. 
By these accounts from the Pen of Baha’u’llah, the seeker has direct access to these moments of Awakening of the Manifestation of God for our Day. Through the Baha’i Firesides, the seeker can confirm, through scientific and revelatory proof, that Baha’u’llah fulfills the prophecies as that great Promised One awaited by all people, and spoken of in all the Holy Books from both east and west. He comes in the prophesied Name, Date, Address & Mission, proving His authenticity, which is the criteria for believability. Investigate!
1. Baha’u’llah, Epistle to the Son of the Wolf
2. Baha’u’llah, Summons of the Lord of Hosts