A wise old Sheikh once lived near a Musjid in Medina. One day the Sheikh heard an impatient pounding on his door. He opened it and greeted a young student, who said, "I have studied with great and wise masters. I consider myself quite accomplished in Islamic teachings and philosophy. However, just in case there is anything more I need to know, I have come to see if you can add to my knowledge."
"Very well," said the wise old master. "Come and have tea with me, and we will discuss your studies." The two seated themselves opposite each other, and the old Sheikh prepared tea. When it was ready, the old Sheikh began to pour the tea carefully into the visitor's cup. When the cup was full, the old man continued pouring until the tea spilled over the side of the cup and onto the young man's lap. The startled visitor jumped back and indignantly shouted, "Some wise master you are! You are a fool who does not even know when a cup is full!"
The old man calmly replied, "Just like this cup, your mind is so full of ideas that there is no room for any more. Come to me with an empty-cup mind, and then you will learn something."