In Hasidut, the rebbe reaches a supreme level of d’veikut — cleaving to God.
The hasid can share in the rebbe’s d’veikut by recounting stories about him.
His d’veikut can become ours, too.
Some of those who have united with God have seen a Light, or their faces shone with a visible light, as it says in Avot d’Rabbi Natan (B):
“Knowledge of Torah can be compared to gold plate. What is gold plate like? As long as a man rubs and polishes gold plate, it shines and brightens his face [by reflected light]. In the same way, as long as you study the words of Torah two and three times, they shine and brighten your face, as it says, ‘The commandment of God is pure, brightening the eyes ‘.” 
Can we see the light they saw by recounting stories about them?
“God said, ‘Let there be light,’ and there was light.
(I’ve also translated this: “God said, ‘Light: Be!’ and Light was.”) 
(Each night, repeat the above verse when lighting the shammash, then read one of the following after saying the brachot and lighting a light/lights.)
“In the light which the Blessed Holy One created on the first day, Adam could see from one end of the world to the other.
When the Blessed Holy One saw the generation of the Flood and the Generation of the Dispersion, and saw that their actions were destructive, He…hid the Light from them…to be given to the righteous in future generations.” 
אור אור אור
“When Mosheh came down from Mount Sinai with the two tablets of the covenant in his hands, he was not aware that his face was radiant because he had spoken with God. When Aharon and all the B’nai Yisrael saw Mosheh, his face was radiant, and they were afraid to come near him. But Mosheh called to them; so Aharon and all the leaders of the community came back to him, and he spoke to them. Afterward, all the B’nai Yisrael came near him, and he gave them all the commands God had given him on Mount Sinai. When Mosheh finished speaking to them, he put a veil over his face. Whenever he entered the Mishkan to speak with God, he removed the veil until he came out. And when he came out and told the B’nai Yisrael what he had been commanded, they saw that his face was radiant. Then Mosheh would put the veil back over his face until he went in to speak with God again.” 
אור אור אור אור
“How glorious was [Simeon ha-Tzaddik, the High Priest] when he came out of the Holy of Holies. He was like the morning star shining through the clouds, like the full moon, like the sun shining on the Temple of the Most High, like the rainbow gleaming in glory against the clouds, like roses in springtime, like lilies beside a stream, like the cedars of Lebanon in summer, like burning incense, like a cup made of hammered gold and decorated with all kinds of jewels, like an olive tree loaded with fruit, like a cypress tree towering into the clouds.” 
אור אור אור אור אור
“Rabbi Yochanan ben Zakkai rose and went outside. Then, Rabbi Eliezer ben Hyrkanos [his disciple] sat down and expounded. His face shone like the light of the sun and his effulgence beamed forth like that of Mosheh, so that no one knew whether it was day or night. They went [outside] and said to Rabbi Yochanan, ‘Come and see Rabbi Eliezer sitting and expounding, his face shining likest the light of the sun and his effulgence beaming liked that of Mosheh, so that no one knows whether it is day or night.’ He came inside behind Rabbi Eliezer and kissed him on his head, saying to him, ‘Happy are you, Avraham, Yitzhak and Yakov, because this one has come forth from your loins!’” 
אור אור אור אור אור אור
“A rich and elegant Roman woman noticed that Rabbi Yehuda bar Ila’i’s face was glowing. She called to him, ‘Old man! Old man! Are one of the following three things true about you? Are you drunk? Are you rich from lending money on interest? Or are you a swine farmer?’
He answered, ‘I swear that none of these three things are true about me. I don’t loan money at interest because it says in the Torah, ‘Don’t charge your brother interest when you loan him money.’ I don’t raise pigs because it’s forbidden for a Jew to raise pigs. I’m not drunk, since I only taste wine when I make Kiddush on Shabbat, and Havdalah after Shabbat, and when I drink the four cups on Passover.’
‘So then why does your face shine?’ she asked.
‘It’s Torah that lights up my face, as it says, ‘A man’s wisdom lights up his face’.” 
אור אור אור אור אור אור אור
“Rabbi Shmuel of Regensburg’s son, Yehudah, was ignorant and undisciplined until he was 18. At that time, Rabbi Shmuel took his son Yehudah with him to the bet ha-midrash and placed him by his side, while his other son, Rabbi Avraham, he placed on the other side. Then Rabbi Shmuel pronounced the Holy Name and the whole bet ha-midrash was filled with a great light. Yehudah was overpowered by the light, covered his face with his cloak and fell to the ground, not being able to look into the light. Rabbi Shmuel then turned to his son Rabbi Avraham and said to him: ‘This is a favorable hour for my son Yehudah. I know that you [Avraham] have been a great scholar all your life, but your brother Yehudah will learn much more than you. He will know what is taking place in heaven above and on the earth below, and nothing will be hidden from him.’ Yehudah became Rabbi Yehudah of Regensburg, known as Yehudah He-Hasid — Judah the Pious — the leader of the Hasidei Ashkenaz and the author of ‘Sefer Hasidim’.” 
אור אור אור אור אור אור אור אור
“The great Tzadik, Rabbi Nachum of Tchernubal, once saw [Rebbe Nachman of Breslav] as a youth in Medvedevka. He was astounded at the great awe that was visible on the Rebbe’s face…
The Rebbe’s eyes would literally ‘glow like the sun and the moon.’ This was especially true on the holy Shabbat, when his eyes would shine and his face would glow…If you have not seen this, you have never seen anything good.” 
אור אור אור אור אור אור אור אור אור
“When I [Rav Avraham Yitzhak Kook] lived in London, I used to visit the National Gallery, and my favorite pictures were those of Rembrandt. I really think that Rembrandt was a Tzadik. Do you know that when I first saw Rembrandt’s works, they reminded me of the legend about the creation of light? We are told that when G-d created light, it was so strong and pellucid, that one could see from one end of the world to the other, but G-d was afraid that the wicked might abuse it. What did He do? He reserved that light for the righteous [tzadikim] when the Messiah should come. But now and then there are great men who are blessed and privileged to see it. I think that Rembrandt was one of them, and the light in his pictures is the very light that was originally created by G-d Almighty.” 
Some years ago, around 1979 or 1980, I saw Rabbi Gedaliah Koenig, a Breslaver rabbi from Israel, in New York City. He was in New York for several reasons — among them to raise money and support for his community in Tzfat. He was giving private interviews in Boro Park and I went to see him. He didn’t speak English, so there was an interpreter with us. I asked him what he thought about meditation — TM in particular. He was not in favor of it at all. I didn’t feel anything special during the interview and left thinking it had been an interesting experience; nothing more.
Some days later, I saw him speaking in public at the 92nd Street Y. My friend, Miriam Burstein, asked him, “Is there humor in Creation?” He answered, “Siz simchah” — “There’s joy.”
Otherwise, I don’t remember what he was speaking about, nor do I remember him speaking with particular force.
But as he spoke, I saw his face glowing.
I wondered where the light was coming from. I actually turned around to see if there was a spotlight shining on him from the back of the auditorium, but I saw none.
I never heard anyone else mention seeing what I did.
I don’t remember experiencing the same thing with any other of the many spiritual teachers I’ve gone to see and hear.
My strongest memory of the evening was just seeing a man sitting and speaking quietly; his face clearly glowing. 
 Tehillim/Ps. 19:9
 Saldarini S.J., A.J., trans.; The Fathers According to Rabbi Nathan (version B); Brill Publishing, © 1975; p. 184-5
 Bereishith/Gen. 1:3
 Hagigah 12a; also found in the Zohar
 Shemoth/Ex. 34:29-35
 The Wisdom of ben Sirach 50:5-10
This book was known to the rabbis but was not included in the TaNaCh. It does appear in the Septuagint.
The High Priest entered the Holy of Holies (the innermost room of the Temple) only once each year, on Yom Kippur.
Yeshu ben Sirach was an eye-witness to 2nd Temple services, c. 2nd century BCE.
These verses also form the basis of “Mareh Kohen,” a poem/song/prayer in the traditional Yom Kippur Musaf liturgy, in the “Avodah” section.
 (adapted from) Friedlander, G., trans.; Pirke de Rabbi Eliezer; Sepher-Hermon Press; © 1916 , p. 7
 http://www.chabad.org/library/article_cdo/aid/2868334/jewish/Rabbi-Yehudah-bar-Ilais-Glowing-Face.htm_c; based on Nedarim 49b
 (adapted from) Gaster, Moses; Ma’aseh Book; Jewish Publication Society, c. 1934, p. 337-8
 Rabbi Nachman’s Wisdom; p. 310
 (from an article by Avraham Melnikoff in The Jewish Chronicle; London; 13 September 1935, p. 21 (Rav Kook was speaking to A. Melnikoff when he made the statement.)
 This is my own personal report. I’ve never written or spoken about it, but it seemed to fit perfectly into this series of anecdotes.