Old age means nearing death.
Now here Prahlāda Mahārāja, as soon as he saw some opportunity that the teacher is out of the class, he will call all the boys, "My dear friends, this bhāgavata-dharma, this understanding God consciousness or Kṛṣṇa consciousness, should be learned from the very beginning of life." "Why? Let us play. Why bhāgavata-dharma now? All right, if there is Kṛṣṇa consciousness movement, when we shall get older or when the time of death will be nearing, we can study at that time bhāgavata-dharma."
But Prahlāda Mahārāja said, "No." Kaumāra. Why kaumāraṁ? Now, durlabhaṁ mānuṣaṁ janma. You are calculating that when you'll get old, at that time you shall try to understand what is Kṛṣṇa consciousness. But what is the guarantee that you are not already old enough? Who can say? The next moment I can die. Old age means nearing death, but there is no such guarantee that one shall die at eighty years old or hundred years old. Death can take place at any moment. Therefore a sane man will understand that we are always old enough because there is no guarantee. Durlabhaṁ. And this mānuṣaṁ janma, this human form of life is called durlabha. Durlabha means very rarely obtained, after many, many evolutionary process, either you take the anthropologists' theory how human body has developed or you take from Vedic literature. But the difference is that anthropologists, they say, "There is no soul. The organic matter is developing in different ways." But Vedic literature says it is not the organic matter, but it is the soul. The soul is a person, is individual, and he is transforming different types of bodies from one body to another, transmigrating. This we have explained several times.