Jochanan ben Zachaï is asked by Rabi Eleazar ben Aroch for tuition on a chapter of the Mercaba
Type of Spiritual Experience
As described in Spiritism (Western Fakirism) Study Historical, Critical and Experimental - Dr. Paul Gibier 
Today we have the proof that, among the ancient Hebrews, the vernacular text of the law books, whose reading Moses recommended to all, neither Genesis nor the other parts of the Pentateuch were considered by the initiates of the Temple and the synagogues as the complete manifestation of the truth.
A small number of men, being part of what was called Kabbalah, had their own genesis, as well as their own theology and philosophy, unavailable to the common man [sic]. If the documents we have on Kabbalah are very incomplete, it is because of the mode of initiation that took place in the shade of the tabernacles and consisted almost exclusively of oral teaching.
It is likely that the same was true of most initiations: each religion had its own more or less coarse symbolic exoterism intended for the common crowd, and its exoterism, to which only priests were initiated under the most dreadful oath. …………The quintessence of doctrine, or Hermetism, was reserved for a limited number of initiates.
A description of the experience
One day, our master Jochanan ben Zachaï set out on a journey, riding a donkey and followed by rabi Eleazar ben Aroch. He asked him to teach him a chapter of the Mercaba.
'Didn't I tell you', replied the master, 'that it is forbidden to explain the Mercaba to a simple person, in case his wisdom and propitious intelligence are not enough'. –
'That, at least', replied Eleazar, 'I may repeat before you what you have taught me about this science'. –
'Well, speak', replied our master again.
Saying this, he descended to the ground, covered his head and sat on a stone, in the shade of an olive tree....
As soon as Eleazar, son of Aroch, had begun to speak of the Mercaba, a fire came down from heaven, enveloping all the trees of the countryside, which seemed to sing hymns, and from the middle of the fire, we heard a spirit expressing its joy by listening to these mysteries...
...The sky suddenly became overcast with thick clouds, a meteor rather like the rainbow shone on the horizon, and the spirits were seen running to hear them (those who were reciting a chapter of the Mercaba), like curious people who crowd on the way of a wedding.
"The spirits, the souls of the righteous, says the Zohar, a Kabbalistic work, inhabit infinite spaces."
 Or "Histoire du Char", a treatise on cabalistic theology. See the work of Mr. Franck, from the Institute.
 Thal. Bab. Traii, Chaginga, fol. 14, and Jacolliot, op. cit.