“In Die Kabbala, by Franck, the author, following its “esoteric ravings”, as he expresses it, gives us in addition to the translations, his commentaries. Speaking of his predecessors, he says that Simeon Ben-Iochai mentions repeatedly what the “companions” have taught in the older works. And the author cites one “Ieba, the old, and Hamnuna, the old.” But what the two “old” ones mean, or who they were, in fact, he tells us not, for he does not know himself.
Among the venerable sect of Tanaim, or rather the Tananim, the wise men, there were those who taught the secrets practically and initiated some disciples into the grand and final Mystery. But the Mishna Hagiga, 2nd section, say that the table of contents of the Mercaba “must only be delivered to wise old ones.” The Gemara is still more dogmatic. “The more important secrets of the Mysteries were not even revealed to all priests. Alone the initiates had them divulged.” And so we find the same great secrecy prevalent in every ancient religion.
But, as we see, neither the Sohar nor any other kabalistic volume contains merely Jewish wisdom. The doctrine itself being the result of whole millenniums of thought, is therefore the joint property of adepts of every nation under the sun. Nevertheless, the Sohar teaches practical occultism more than any other work on that subject; not as it is translated though, and commented upon by its various critics, but with the secret signs on its margins. These signs contain the hidden instructions, apart from the metaphysical interpretations and apparent absurdities so fully credited by Josephus, who was never initiated, and gave out the dead letter as he had received it.”
H. P. Blavatsky
The Mark Of God: Understanding Your "I AM Presence" 