This is a very nice lecture by His Divine Grace from the sixth Canto of the Srimad Bhagavatam, recorded July 12th, 1975, in Philadelphia, PA.
…We are thinking, “I shall be happy in this way. I shall be happy in this…” Nothing. You shall never be happy—this is perfect instruction—unless you go back to home, back to Godhead. Just like a mad boy, he has forsaken his father. His father is rich man, everything is there, but he has become hippie. So similarly, we are also like that. Our father is Kṛṣṇa. We can live there very comfortably without any botheration, without endeavor for earning money, but we have decided that we shall live here in this material world. This is called ass. … Therefore mūḍha. We do not know what is our self-interest. And we are hoping against hope, “I shall be happy in this way. I shall be happy in this way.” Therefore this word is used, mūḍha. They do not know what is actually his happiness, and he is trying one chapter, another, one chapter, another, “Now I will be happy.” The ass. The ass. Sometimes the washerman sits on his back and takes a bunch of grass and puts in front of the ass, and the ass wants to take the grass. But as he moving forward, the grass is also moving forward. (laughter) And he thinks, “Just one step forward, I shall get the grass.” But because he is ass, he does not know that “The grass is situated in such a way that I may go on for millions of years; still, I will not get the happiness…” This is ass. He does not come to his senses that “For millions and trillions of years I may try to be happy in this material world. I will never be happy.”
The Hare Krishna Movement 