In India there was once a king named Vikramāditya. He had so many “jewels”—his counsellors—nine court jewels. All nine were highly learned, but among them Kalidāsa was supremely intelligent. One day a person looking like a madman came, holding a skull in his hand. He was quite naked and very dirty. He came in the council of Vikramāditya and put that skull on the desk, saying, “I have heard there are many intelligent jewels in your court. Let them come here and test whether the person whose skull I have placed here was intelligent or a fool and a rascal.”
Eight jewels were there, very learned persons, participating in the king’s council, but none of them were able to reply. Only the skull was there, nothing else, so how could they test it? Then that madman began to laugh and said, “You are all bogus, foolish persons with no sense. I had heard this, and now I have found out that it is true. So I am going.” And he took the skull, preparing to leave. In the meantime, Kalidāsa came. The King requested the madman, “Oh, wait a little. another one of my counsellors is coming, and he will answer your question.”
That person put the skull on the desk again, and Kalidāsa came. This same question was asked to Kalidāsa, who then took a long coconut stick made of very fine, long strands used for sweeping and went to the skull. He put the stick in one ear and it came out the other side, through the other ear. Then he said, “Your question is answered. Do you understand?”
“Oh, you should clarify more,” the King said. “I do not understand.”
Kalidāsa explained, “If anything comes in one ear and goes out the other, that person is surely foolish. And if something goes in one ear and does not come out the other, but instead goes into the heart, then he is surely a very intelligent person. Thus, from his skull we can understand that this dead person was very foolish.”
If we hear so many things but do not take them into the heart, if we do not cultivate all these teachings, then we are like a foolish person and cannot develop our kṛṣṇa-prema. You have come from many distant, far-away places. So don’t merely take these teachings in one ear and let them go out the other, but keep them in your heart and follow them.

―Śrīla Bhaktivedānta Nārāyaṇa Mahārāja