It happened to a rabbi who had no children that after a long while an only son was born to him. He brought him up and took a wife for him. The son sat on the upper floor and studied, as is the wont of the sons of rich men. He always studied and prayed. Nevertheless he felt it in himself that he was deficient in something, but he did not know what it was he lacked. He felt that his study and his prayer had no meaning for him. He told about this to two youths, who advised him to go to a certain Tzaddiq. Once the son performed a mitzva [an important religious deed] through which he achieved the rank of a Small Luminary.
The son went and told his father that he found no meaning in his study and in his service [of God], and that he lacked something but did not know what, and therefore he wanted to go to that Tzaddiq. His father replied to him: "Why should you want to go to him, when you are a greater scholar than he and are of nobler descent? It is not seemly that you go to him. Give up this plan!" Thus he prevented him from going.
The son returned to his studies, and again felt a deficiency in his soul. He again took counsel with the same men, and they again advised him to go to the Tzaddiq. He went again to his father, and his father prevented him from going to the Tzaddiq this time too.
The son continuously suffered from his deficiency and desired greatly to remedy it, but he did not know what it was and how to remedy it. Finally he went to his father and entreated him very much that he should let him go to the Tzaddiq. His father could not refuse him, and was forced to travel with him, for he did not want to let his only son travel alone. And his father said to him: "Behold, I shall go with you and show you that there is no substance in him!"
They hitched up the cart and departed. His father said to him:
"Let this be a sign for us: if our journey goes smoothly, the thing is from heaven. But if not, it is not from heaven, and we shall turn back."
They traveled. They came to a small bridge. One of the horses fell and the cart turned over, and they almost drowned. His father said to him: "You see, our journey is wrong. It is not from heaven." They returned home.
The son returned to his studies, and again felt the deficiency, and did not know what it was. He again importuned his father about the journey. His father was forced to go with him a second time. And again made a condition as he did the first time: "If the journey goes smoothly, fine; but if not, it is not from heaven." The axle of the cart broke. His father said to him: "Again our journey has proved to be wrong. The matter is not from heaven." So they turned back again.
The son returned to his studies but they did not progress satisfactorily. His deficiency gave him no rest. He importuned his father that he should go with him this time without any condition and without any sign. The signs mean nothing-it is quite an ordinary thing that a horse should fall occasionally, or that the axle of a cart should break.
They traveled and came to an inn to stay overnight. They met there a merchant, and began to talk to him as is the wont of merchants. They did not tell him that they were on their way to that Tzaddiq, for the rabbi was ashamed to divulge such a thing. They talked about the affairs of the world. In the course of their talk the matter of Tzaddiqim came up, and where Tzaddiqim were found. The merchant told them that here lived a Tzaddiq, and there, and there. They began to talk about the Tzaddiq to whom they were going. The merchant said: "That one! He is of little worth. I am just coming from him. I was there and saw that he was guilty of a transgression." The father said to his son: "Do you see? This merchant is talking casually, and he has just come from there!" And they returned home.
The son fell ill, and departed from the world. Then he came in a dream to his father. His father saw him standing in great wrath. He asked him: "Why are you angry?" He answered him: "Go to that Tzaddiq, and he will tell you why I am angry." The father woke up and thought: "It happened by chance." Then he dreamt a second time. He said: "This, too, happened by chance." And so it happened three times. Finally he took the matter to heart and went to that Tzaddiq. On the way he entered an inn to rest. It so happened that it was the same inn where he stayed with his son the previous time. He also met there that merchant whom he and his son had met the first time. He recognized him and asked him: "Are you he whom I saw then?" The merchant replied: "Certainly you saw me then."
And then the merchant opened his mouth and said: "Do you remember, when you traveled with your son, at first the horse fell on the bridge, and you turned back. Then the axle broke, and you turned back. The third time you met me and I told you that he [the Tzaddiq] was of no value, and you turned back. Now that I have dispatched your son, now you are permitted to complete your journey. For be it known to you: Your son had the rank of a Small Luminary, and that Tzaddiq has the rank of a Great Luminary. Had they met and joined forces, the Messiah would have come. But since I dispatched him, you are permitted to go on. "Thus he spoke and disappeared. The rabbi stood amazed. There was nobody with whom he could have spoken.
He continued his journey to the Tzaddiq. He came to him and cried: "Woe, woe! Woe for those who are lost and cannot be found!"
May the Name, blessed be He, return our exiles soon, Amen!

(Nahman of Bratzlav, Sippure Ma'asiyyot, story no. 4, pp. 22-24.)

Source: Raphael Patai, The Messiah Texts, Wayne State University Press