The holy Rebbe Reb Bunim of Peshischa used to tell those who came to him to become his students the following story:

In the city of Krakow is a shul called Reb Isaac Reb Yeikel's shul, after the man who built. His story is as follows. Reb Isaac was a very poor man who lived in Krakow. One night he had a dream in which he was shown that there was a very large treasure buried near a big bridge in the city of Vienna. He was shown all the surroundings so that he could recognize it. When it was morning, he decided to ignore the dream, since afterall most dreams are just foolishness. But he had it again the next night, and continued to have it. He finally could not hold himself back, and he set out to Vienna to see if there was any truth in the dream.
When he got there he saw the bridge exactly as it had been in his dream, and he could even recognize where the treasure was buried. But there was a problem. The bridge was near a palace which was surrounded by guards, who didn't look like they would be so happy to let him start digging a hole there. So everyday he went out to look around to see the bridge, and maybe some idea would come to him as to how he could get the treasure that was there.
After a few days of this the guards began to suspect him. Afterall what purpose is there for a Jew to come and look around the palace everyday? So the head of the guards came over to him and say, 'Jew, what do you want here?' So Reb Isaac explained to him his dream and the purpose of his coming. After hearing the story the guard broke out in bellowing laughter that could be heard in the whole city if Vienna. 'You stupid Jews', said the guard. 'If I was as foolish as you, following my dreams after buried treasure, you know what I would have done? I would have gone to Krakow and dug under the oven of some Jew named Isaac the son of Yeikel. Why half the Jews are called Isaac and the other half Yeikel. How stupid you Jews are.'
On hearing the words of the guard he replied, 'Yes, I suppose you are correct. Thank you for setting me straight. I shall now return home.' So he returned home, and dug under his oven and found a huge treasure. With part of it he built the shul [which still stood until World War 2].
The Rebbe Reb Bunim would say that when one goes to a Tzaddik in order to learn how to serve HaShem, he shouldn't think that he is going to find something there. The Tzaddik can only help him to bring out that which is within him.