The circumstances of the accession to the Brahma Sabha by Babu DebendraNath in 1838 are most noteworthy.
Belonging to one of the wealthiest of Calcutta families, he would spend his time, as is too often the wont of the aristocracy, in the trivialities of fashion, until, in God's great mercy, he was suddenly and deeply impressed with the vanity and mortality of all worldly pleasures. In the yearning of his soul after a higher life he was led to the Brahma Sabha. Having once joined the body, he threw himself with all the fire of an awakened heart into the work of the Church, but he soon found that there was a sad lack of depth in the movement.
As left by Raja Ram Mohan Roy the Samaj was really nothing more than a mere platform, where men of various creeds met from time to time to listen to the hymns and sermons. By joining it nothing was lost, nothing incurred, nothing pledged. Indeed, there were not a few who would attend the service at the Samaj in the morning and worship idols at home in the evening, thus showing that they had never really grasped the meaning of spiritual devotion.
Hence, in the year 1839, DebendraNath a started the Tattvabodhini Sabha, or Truth-teaching Society, and established various schools at different places, so that young men might be trained for national service in the Adi Brahmo Samaj and to propogate the spiritual researches of Raja Rammohun Roy.
A concise introduction
1. Rammohan Roy and Dwarkanath Tagore establish Brahma Sabha to practice Rig Vedic arts.
2. Debendranath Tagore is initated into Vedic rites of his father and grandfather by Ram Chunder Vidyavgish. After the death of his grandmother (Rammohan's 4th wife) he has an out of body experience and devotes his remaining life to discovering Brahma. Brahma allows him a single glimpse which transforms him and causes Debendranath to withdraw from this world.
3. His successor Hemendranath carries on from his father's experiences and in 1861 is able to levitate. In 1862 and 1863 Hemendranath retreats twice to the Himalayas, by now he is able to control Time and Space. In 1863 he initiates as a disciple another Brahmin : Shyama Charan Lahiri (Dev Sharma) in Rishikesh. Shyama Charan goes on to become the Mahasaya Lahiri (founder of Kriya Yoga and personage who initiates Shirdi Sai Baba). In 1885, people claim to have seen Hemendranath Tagore (after his death) in the garb of a yogi flying in the Sunderbans - the Sunderban Yogi.
In about 1795, Rammohun Roy and Harihara Tithankara secretly co-wrote the Maha Nirvana Tantra (MNT). This work contained the following rules for Gayatri devotion which has been used ever after by the Adi Brahmos.
Among all texts the Gayutree is declared to be the most excellent;
the worshipper shall repeat it when inwardly pure, reflecting on the meaning of it, If the Gayutree be repeated with Om and the Vyahriti (viz. Bhooh, Bhoovuh, Swuh), it excels all other theistical knowledge, in producing immediate bliss.
Whosever repeats it in the morning or evening or during the night, while meditating on the Supreme Being, being freed from all past sins, shall not be inclined to act unrighteously.
The worshipper shall first pronounce Om, then the three Vyahritis, and afterwards the Gayutree of three lines, and shall finish it with the term Om.
MEANING
We meditate on him from whom proceed the continuance, perishing, and production of all things who spreads over the three mansions ;
That eternal Spirit, who inwardly rules the sun and all living creatures ;
Most desirable and all-pervading ; and who, residing in intellect, directs the operations of the intellectual power of all of us material beings.
The worshipper, by repeating every day these three texts expressing the above meaning, attains all desirable objects without any other religious observance or austerity.
"One only without a second" is the doctrine maintained by all the Oopunishuds : that imperishable and incomprehensible Being is understood by these three texts.
Whoever repeats them once or ten, or a hundred times, either alone or with many others, attains bliss in a proportionate degree.
After he has completed the repetition, he shall again meditate on Him who is one only without a second, and all-prevaling : thereby all religious observances, though not performed, shall have been virtually performed.
Any one, whether a householder or not, whether a Brahmun or not, all have equal right to the use of these texts as found in the Tantra.