Excerpts from The Surangama Sutra
Then King Prasenajit stood up and said to the Buddha, “Before I was instructed by the Buddha, I met Kātyāyana and Vairāṭiputra.  Both of them said that after this body dies, we cease to exist and become nothing. That very nothingness itself is what they called nirvana. Now, though I have met the Buddha, I still have doubts that make me cautious. How can I come to realize the true and fundamental mind that neither comes into being nor perishes? All in this great assembly who have outflows wish to hear the answer.”
The Buddha said to the king, “May I ask, is your body as indestructible as vajra, or is it subject to decay?”
“World-Honored One, this body of mine will keep on changing till in the end it will perish.”
The Buddha said, “Your Majesty, you have not perished yet. How is it that you know you will perish?”
“World-Honored One, my body is impermanent and subject to decay, although it has not perished yet. But now, upon reflection, I can see that each one of my thoughts just fades away, followed by a new thought which also does not last, like fire turning into ash, constantly dying away, for-ever perishing. By this I am convinced that my body, too, must perish.”
The Buddha said, “So it is. Your Majesty, you are in your declining years. How do you look now, compared to when you were a boy?”
“World-Honored One, when I was a child, my skin was fresh and smooth, and I was full of vital energy when in my prime. But now in my later years, as old age presses upon me, my body has withered and is weary. My vital spirits are dulled, my hair is white, my skin is wrinkled. Not much time remains for me. How can all this compare to the prime of life?”
The king has reached a point where his body no longer helps him out. His body is oppressive and nags at him to move somewhere else. It will soon be unlivable. (II, 36)
The Buddha said, “Your Majesty, your body’s appearance cannot have deteriorated suddenly.”
The king replied, “World-Honored One, the change has in fact been so subtle that I have hardly been aware of it. I’ve reached this point only gradually through the passing of the years. Thus when I was in my twenties, I was still young, but I already looked older than I did when I was ten. My thirties marked a further decline from my twenties, and now, at two years past sixty, I look back on my fifties as a time of strength and health.
“World-Honored One, as I observe these subtle transformations, I realize now that the changes wrought by this descent toward death are evident not only from decade to decade; they can also be discerned in smaller increments. Considering more closely, one can see that changes happen year by year as well as by the decade. In fact, how could they happen merely year by year? Such changes happen every month. And how could they occur from month to month only? These changes happen day by day. And if one contemplates this deeply, one can see that there is ceaseless change from moment to moment,  in each successive thought. Thus I can know that my body will keep on changing till it perishes.”
The Buddha said to the king, “Observing these changes — these never- ceasing transformations — you know that you must perish. But do you also know that when you perish, something in you does not perish with you?”
Putting his palms together, King Prasenajit replied to the Buddha, “Indeed I do not know.”
The Buddha said, “I now will reveal to you what it is that does not come into being and does not perish. Your Majesty, when you first saw the River Ganges, how old were you?”
The king replied, “I was three when my beloved mother took me to pay respects to the goddess Jı̄va.  When we went past a river, I knew that it was the Ganges.”
The Buddha said, “Your Majesty, you said that when you were in your twenties, you had already aged compared to when you were ten. Year after year, month after month, day after day, in each successive thought there have been changes till you have reached your sixties. Consider, though: when you were three years old, you saw the river; ten years later, when you were thirteen, what was the river like?”
The king replied, “It looked the same when I was thirteen as it did when I was three, and even now, when I am sixty-two, it is still the same.”
The Buddha said, “Now you are mournful that your hair is white and your face is wrinkled. Your face is certainly more wrinkled than it was when you were in your youth. But when you look at the Ganges, is your visual awareness any different from your visual awareness as it was when you saw the river in your boyhood?”
The king replied, “No different, World-Honored One.”
The Buddha said, “Your Majesty, your face is wrinkled, but the essential nature of your visual awareness itself has not wrinkled. What wrinkles is subject to change. What does not wrinkle does not change. What changes will perish. But what does not change neither comes into being nor perishes. Then how could it be affected by your being born and dying? So you have no need to be concerned with what such people as Maskari Gośālı̄putra  say: that when this body dies, you cease to exist.”
The king believed the words that he had heard, and he understood that when we leave this body, we go on to another. He and all the others in the great assembly were elated at having gained a new understanding.
 Kātyāyana and Vairāṭiputra were contemporaries of the Buddha who taught forms of skepticism. This Kātyāyana is said to have been a fierce opponent of the Buddha; he is not to be confused with the Buddha’s disciple Mahākātyāyana.
 A material of extreme hardness and durability.
 Skt. kṣaṇa.
 Skt. jīva means “the principle of life.”
 The king mentioned above that the non-Buddhist teachers expressing this view were Kātyāyana and Vairāṭiputra. Here the Buddha mentions instead Maskāri Gośālı̄putra, presumably because Maskari was named first in a standard list of six major non-Buddhist teachers (Ch. wai dao liu shi, 外道六師) who were contemporaries of the Buddha.