(Prabhupada's lecture - Śrīmad-Bhāgavatam 1.16.5 - Los Angeles, January 2, 1974)
So the..., this is the aspiration of the karmīs, to elevate life to higher standard of life. As the world is going on... The struggle is going on for having a higher standard of life. But they are becoming implicated. Now, there was bull-drawn cart or horse-drawn carriages. Now they have got nice cars also, but the problem is petrol. So the karmī world is like that. You create one kind of happiness, but side by side you create another kind of unhappiness. This is called karmī-yoga. Just like if you want to raise one big skyscraper building, then you have to dig somewhere to get the earth to make the bricks and the iron. You cannot manufacture without taking help of the nature.
So if you raise here, you must dig here. This is karmī-yoga. If you want to enjoy something extraordinarily, you must create another unhappiness extraordinarily. This is called karmī. Therefore they are mūḍhas. Mūḍhas means rascals, asses. They do not know that "By increasing every year new motorcars, I am creating another problem. If there is no petrol, then the whole business will be spoiled." That they do not know. And because they do not know, they are called asses, mūḍha. The effect they do not know. So the tri-daśa-pūr, going to the heavenly planet... Just like they are going to the moon planet, but problems after problem, contemplating how to make a platform in the sky to get petrol. The problem is there, not that very easily going. The problematic... Things are problematic.