Kṣudrāyuṣāṁ nṛṇām. Kṣudra, means very small, āyuṣām, duration of life. As we can compare that an ant's life or a germ's life... They are also living entities. Their duration of life is very small. There are many flies, they take their birth at night, in the evening, and the whole night they are busy, the same way: eating, sleeping, begetting children and being afraid of. All the qualities are there. In India we have got experience. They are called diwali germs or insects. In the evening before the light—one, two, three—in this way, by midnight, it increases to thousands and millions. And in the morning, at the end of the night, you will find heaps of insects or dead body. Heaps. Millions.
So there are different grades of life. It is called mṛtyu-loka. This material world is called mṛtyu-loka: "where everyone dies." But there are grades of duration of life. One living entity has got four minutes life, another, ten minutes, another, hundred minutes. Then days. One day, hundred days. Then year. One year, or four year, or five year, or utmost, hundred years, on this planet. So the human being can live up to utmost hundred years, but in other planets there are other living entities, demigods. And the highest, the topmost planet is Brahmaloka. And you have learned from Bhagavad-gītā, in the Brahmaloka, the duration of life, to our calculation, is very, very long. Sahasra-yuga-paryantam ahar yad brahmaṇo viduḥ (BG 8.17). In the Brahmaloka, the duration of twelve hours, our twelve hours, morning to evening, that is many millions of years to our calculation. So even if you go to that planet Brahmaloka, as you are trying to go to the moon planet... From śāstra we understand in the moon planet, they live up to ten thousands of years according to heavenly calculation. In each planet, in each society, the calculation is different. So it is calculated that in the moon planet you can live for ten thousands of years, and that calculation is compared: our six months equal to one day in that planet. So just imagine how many years of our calculation they can live.