Ass is working hard for the washerman, not for himself, and still, he thinks he is happy. Therefore these four nice animals has been exemplified. That is our life. The karmīs are compared with the ass. Big, big businessmen, day and night working hard, earning money, not for himself. What he will eat? Two cāpāṭis, that's all. Or little milk or little... Not that he has earned 1000 dollars every day and he will eat it. No. He will eat, out of that 1000 dollars, he will eat fifty cents, and balance will be eaten by others.
You see. But still, he is working hard. And the example is ass. The ass takes a morsel of grass. It is worth nothing. The ass can get anywhere the morsel of grass. But still, he thinks that the washerman is feeding me. So he remains there. And in Mexico you found some asses, carrying loads. So they are carrying loads, very heavy loads, tons, for that morsel of grass, which he can get anywhere. But he thinks, "Oh, I will die. If my master does not give me a morsel of grass, I will die. So let me remain here and carry all the big loads." You see. Similarly, the karmīs, they remain at home. They think that "My wife, my children, my family—without them, I shall die. So I have to work to maintain them like an ass." That's all. The karmīs, they are working, accumulating bank balance, more, more, more, more, more, more. But forgetting the real mission of life. Therefore ass. Ass means fool. Whenever one man is called, "You are ass," that means he's a fool. So this human form of life, so valuable...
To realize Kṛṣṇa and go back to Him, that should be our main business. But these karmīs, they do not know what is the mission of this human form of life. They are busy working hard, day and night, for a morsel of grass. That's all. Yan maithunādi-gṛha... There are many other verses.