The Voice in the Room
It is told that in 5487, when the Ramchal was twenty, he was reciting a yichud on Rosh Chodesh Sivan when he fell into a trance. As he awoke, a voice said that it had come down to uncover the concealed mysteries of the Holy King. He stood trembling for a while, then steadied himself, and the voice revealed a secret to him.
The next day he arranged to be by himself in the room at the same hour, and the voice returned with another secret. Eventually it told him that it was a maggid sent from Heaven, and it gave him yichudim to recite whenever he wished it to appear again. He never saw the maggid. He heard its voice speaking through his own mouth, and he was allowed to put questions to it.
After about three months, the maggid taught him the yichudim that would make him worthy of a revelation from Eliyahu HaNavi. He was then charged with writing a work on Koheles, on the mystical meaning of its pesukim, and Eliyahu came and shared secrets of his own. The maggid said that Metatron would come as well, and that the Ramchal would know him by what Eliyahu had said. From then on he recognized each visitor. Each day he recorded the new ideas they taught him, and while he lay with his face to the ground, he saw the holy souls whose identity he knew in human form, as in a dream.
His talmid Rav Yekusiel Gordon described these events in a letter to a prominent Italian rav, at a time when the Ramchal was twenty-two. He wrote that the angel spoke out of the Ramchal's mouth while the talmidim heard nothing, and that the Ramchal would then call Eliyahu to come and reveal secrets of his own. At times Metatron came too, together with the Faithful Shepherd, Avrohom Avinu, Rav Hamnuna the Elder, Moshiach and Odom. The maggid had ordered the Ramchal to compose a book of Zohar, which is called in Heaven the Second Zohar. Rav Yekusiel added that no one outside their circle knew of it, and that no one since Rav Shimon bar Yochai had merited such a thing.
In his letter to Rav Binyomin HaKohen, the Ramchal wrote that God-fearing people came to him each day to hear the new things Hashem told him. Many young men who had walked in the empty ways of youth had returned to Hashem and came to him for tikkunim for their past deeds. He credited all of this to Hashem's love and not to his own preparation, while noting that for years he had been careful to recite yichudim, a different one nearly every fifteen minutes.