The first moments of prophecy were apparently quite capsizing and riotous.
As Ramchal puts it, “when a prophet would begin to prophesize he would
first experience a great trembling”, as “all his limbs would quiver and
quake”. He then begins to “lose consciousness” and enter into a trance.
Understand of course that the prophet wouldn’t be apoplectic or suddenly
suffering a seizure, though that must be what he seemed to be going
through to the observing eye. He wasn’t ill or crazed either. What was
happening was that a part of his personhood was being undone by the
presence of G-d and shifting about, and was being replaced by what we
could only term a full-bodied, supernatural personal receptivity to
whatever G-d would be infusing him with.
He would then begin to experience the sorts of visions that only true
prophets would merit seeing, which Ramchal terms “revelations of (G-d’s)
Glory”. And the prophet would then understand that he was indeed being
made privy to what “Supernal Wisdom deemed he should know”.
The prophet Isaiah described the following quite unearthly moment that
could serve as an example of what happened. “I saw the L-rd sitting on a
high and exalted throne,” he said, “and His lower extremity filled the
Temple. Seraphim stood above Him, with six wings … each; with two (each
one) would cover his face, and with two he would cover his feet, and with
two he would fly. Each one called out to the other and said, ‘Holy, Holy,
Holy is the L-rd of Hosts; the whole earth is full of His glory!’ The
doorposts quaked from the voice of him who called, and the house became
filled with smoke. And I said, ‘Woe is me … for my eyes have seen the
King, the L-rd of Hosts” (Isaiah 6:1-5).
It goes without saying that not everyone merited such revelations. One had
to have managed to “attach himself unto G-d’s presence” to a very great
degree, in Ramchal’s words, which of course implies involving oneself in
all sorts of intellectual, prayer-centered, and mystical practices, and
being of the highest moral caliber.
That would enable a potential prophet to achieve “great spiritual stature”
and to then be granted the ability to “perform all sorts of miracles and
wonders” depending on his standing, aside from his communications.
Rabbi Yaakov Feldman has translated and commented upon "The Gates of Repentance", "The Path of the Just", and "The Duties of the Heart" (Jason
Aronson Publishers). His works are available in bookstores and in various
locations on the Web.