"I had a dream (when I was in Izbicza) that they were revealing to me some aspects of the root of my soul. The general thing that was told to me was that the generation of Moshiach will be the same souls as the Generation of the Midbar (Moshiach is the soul of Moshe as mentioned in Zohar, Pinchas 246b).
And those very souls were the Generation of the Mabul (Moshe was also there as mentioned in Zohar Pinchas 216b and Chullin 139b). At the time of the Mabul they had corrupted their ways and committed the sin known as "the sin of youths," and so it is stated "the heart of Man is evil from youth."
The rectification of this was in the Generation of the Midbar. Thus it is called "the kindness of youth" (as it known that the meaning of person's desires/lust is called his kindness), as it is stated "I remember the kindness of your youth."
The Generation of Moshiach will be in the sense of "you shall renew like an eagle of your youth." That generation will be the same generation of "the kindness of youth," that they will renew for a second time.
Rabbi Yitzchak Isaac Yehuda Yechiel Safrin of Komarno (1806-1874) was a Hasidic Kabbalist who was known for his asceticism and mysticism. From a very young age he was acknowledged to possess telepathic powers. The following is an account from his son, where Rabbi Safrin's telepathic powers were tested.
"I will write one account that I heard from him [Rabbi Safrin's study partner]. One time he was in the middle of learning Gemara with his study partner and my father told him: 'This Tannaitic sage had this spiritual nature [tzurah] and this Tannaitic sage had that spiritual nature. This is what he told him about every Tannaitic sage as they learned. And so his did for each Amoraitic sage.'
"When his study partner heard this he wanted to test him to see whether it was true. The study partner said to him: 'I do not have to believe you that you see and know the spiritual nature of the Tannaitic and Amoraitic sages from what you have learned.'
"My father replied: 'If you want to know if the truth is with me, take a piece of paper and write down the names of men, women and children in this city of Pintshov, for you know that I do not know anyone in this city. Also, if you want, you can write names of people from a different city.
"Immediately his study partner agreed to the plan. He wrote down names of men, women and children and the names of their mothers from this city of Pintshov after investigating the people of the city for three straight days. Afterwards, his study partner came before my father with the names of the people in the city and from outside the city; all of these were people that the study partner personally recognized. There were about three hundred names on the paper. My father told him about each person's character; if he was a Torah scholar or ignoramus, a G-d-fearing person without Torah knowledge or a wicked person, a worker or an infant, a rich person or a poor person. For each person he was correct.
"His study partner wanted to test him more so he wrote fictitious names. My father replied: 'What have you done! These names are not found in these cities!' Immediately he acknowledged the truth.
"When the study partner told me this story he wept greatly and said: 'I am not allowed to tell you more of the things that I saw with my eyes since I agreed to not reveal these matters to anyone.'"
Rav Shlomo Wolbe, in his intellectual biography of his teacher and guide, Rav Yerucham Levovitz, describes how Rav Yerucham testified about himself that his dreams often foretold future occurrences:
"He himself recounted in a bible lecture, when he was teaching the section of Mikeitz and the meaning of Pharaohs dreams, that on many occasions he saw future events…When he was in Poltava [Ukraine] he woke up in the morning and said that Reb Nachum of Kelm passed away. In that period of war the lines of communication between Russia and Lithuania (which was conquered by Germany) were completely cut off. His students kept his dream in mind and when they returned from Poltava it became known that indeed Reb Nachum passed away exactly on that day as our teacher had said." (Adam Bikar, p. 22)
"Reb Feival would tell how one day, when walking in the road, the image of his beloved teacher, Rabbi Samuel Rosenberg, appeared in front of him and ordered him to stop. Reb Feival halted - and quickly realized that had he not done so, a car would have struck him down. In gratitude, he vowed to name his next child for Rabbi Rosenberg, and so his sixth child bears the name of his great master." (Men of Spirit, p. 559)
"The event took place in the community of Serahai, where the Gaon lived for some time in the home of his son's father-in-law, who served as the local rabbi. His disciple Menachem Mendel stayed with him there, and it was he that wrote down the interpretation of Song of Songs. When the Gaon had nearly finished the commentary, the Gaon invited his son's father-in-law and his son Judah Leib to join him. The Gaon asked to have the windows closed and that many candles be lit, although it was still full daylight:
"And when he completed his interpretation he raised his eyes on high with mighty devotion, blessings and thanks to His great Name, may it be blessed, Who enabled him to conceive the light of all the Torah from within and from without. Thus he said, All the wisdoms are needed for our holy Torah and are included within it, and he mastered all of these perfectly. And he recalled all of them: the wisdom of algebra and triangles and geometry and the wisdom of music...and of the wisdom of philosophy, [The Gaon] said he knew it perfectly. And he brought only two good things out of it...and the rest must be thrown out. Then he said, thank God the entire Torah, which was given at Sinai, he knew it thoroughly, and all of the Prophets and Writings and mishnayot and the oral law, how they are hidden in it, and no doubt was left to him about any Halakhah or sugiya in the whole Torah in his old age, and he knew the entire oral Torah and all the Halakhic authorities up to the recent ones on the Shulhan Arukh, and he clarified them and shined light onto darkness of flawed readings;...and in hidden things all that was in our possession, the Zohars and the Tiqunei Zohar and Sefer Yezira and the writings of the ARI of sacred memory and the PARDES, he studied them and knew them...And he revised them with evidence as clear as sun; only two grave things in the mysteries of the Torah of the Zohar were questionable to him...And those, if he knew who knew them, he would go on foot to him and then wait for our righteous messiah, and with this he finished."
The Gaon of Vilna: The Man and His Image, by Immanuel Etkes; Quoting Hakdama to Pe'at HaShulkhan by Rav Yisrael of Shklov.
"I will never forget the Simchat Torah I spent with him [Reb Yeruchum Levovitz]. He gave an incredibly powerful inspirational talk. After each section of the discourse we sang "Happy is Israel!" He sang and danced with his hands spread upwards to heaven, with his disciples crowded below dancing across from him. At the end of the discourse he came down from the Aron Kodesh and began a dance which caused every eye to pour forth with tears over the cascade of holy feelings. How wonderful was this image! Hundreds of disciples, among them giants of spirit themselves, dancing, crying and singing. Our master and teacher [Reb Yeruchum] himself said at this time: 'I do not know which is more precious to the Creator of the world - our Yom Kippur or our Simchat Torah!'"
קשה לי מאד לעסק בעניני הלכה לבד, וכן בעניני אגדה לבד, בעניני נגלה לבד, ובעניני נסתר לבד. כמו כן קשה לי לנטות ברעיון בדרך אמונה פשוטה לבד, או בדרך מחקר והגיון לבד. וכן בתכונת ההתבודדות לבד, ובתכונת הרעות והחברותיות לבד. כי כל הזרמים שולטים בי - האמונה והחקירה, הלאמיות והמוסר, ההלכה והאגדה, הנגלה והנסתר, הבקרת והשירה, את הכל אני מכרח לספג.
מרן הרב קוק, חדריו, קכא