(Prabhupada's lecture - Śrīmad-Bhāgavatam 1.15.46 - Los Angeles, December 24, 1973)
This description of the Kali-yuga is given in the Śrīmad-Bhāgavatam. This is called śāstra. This Śrīmad-Bhāgavatam was written five thousand years ago when the Kali-yuga was to begin. Now, what will happen in future, everything is given there. Śāstra means... That is...Therefore we accept śāstra. Tri-kāla-jña. The śāstrakāra, or the compiler of the śāstra, must be liberated person so that he can describe past, present and future. In the Śrīmad-Bhāgavatam you will find so many things which was told to be happening in future. Just like in the Śrīmad-Bhāgavatam there is mention of Lord Buddha's appearance. Similarly, there is mention of Lord Kalki's appearance. There is mention of Lord Caitanya's appearance, although it was written five thousand years ago. Tri-kāla-jña. Know, they know what is past, present and future.
So about the Kali-yuga, discussing, the Śukadeva Gosvāmī is describing the chief symptoms of this age. The first symptom he says, tataś ca anu-dinam. With the process of this age, Kali-yuga, dharma, religious principles; satyam, truthfulness; śaucam, cleanliness; kṣamā, forgiveness; dayā, mercifulness; āyuḥ, duration of life; balam, bodily strength; smṛtiḥ, memory... Just count how many. Dharmaḥ, satyam, śaucam, kṣamā, dayā, āyuḥ, balam, smṛti-eight. These things will gradually reduce to nil, almost nil. Now as I told you, the Kali-yuga... In other yugas... Just like Satya-yuga, the duration of Satya-yuga was eighteen hundred thousands of years. And the human being was living in that age for one hundred thousands of years. One hundred thousands of years. The next age, the duration of that age, twelve hundred thousands of years, and the people used to live for one thousand years, not over ten thousand years. Ten times reduced. The next age, Dvāpara-yuga, again ten times reduced. Still, they used to live for one thousand years, and the duration of the age was eight hundred thousands of years.
Now, the next age, this Kali-yuga, the limit is one hundred years. We can live utmost up to one hundred years. We are not living one hundred years, but still, the limit is one hundred years. So just see. Now, from one hundred years... Now in India the average age is about thirty-five years. In your country they say seventy years? So it is reducing. And it will so reduce that if a man lives for twenty to thirty years, he will be considered grand old man, in this age, Kali-yuga. So āyuḥ, duration of life, will reduce.