user11541: Buddha says all phenomenon are nonself. If understanding is a phenomenon then my understanding of Dhamma will fade away and I will again fall into ignorance.
So my question is: is understanding a phenomenon?

user111: Understanding is caused. Understanding cannot be gained at will. Otherwise we wouldn't have to study, meditate or cultivate the mind. Understanding in reality means a thought or a sequence of thoughts. Thoughts arise and fall all the time. But once you uproot a defilement, it cannot be associated with thoughts again. Once you uproot ignorance, it cannot be associated with subsequent thoughts.     

user5000: 
"Is understanding a phenomenon?"

Yes.
Now you're thinking: "When understanding ceases, I'll fall again into ignorance".
No, no my friend.
Now you're thinking why?
Because: when all phenomena cease, there is no ignorance. Think about it ... How could there be ignorance, if all phenomena ceased?? When all ceases, there is nothing that can be ignorant.
Ignorance is like clinging onto an apple with worms inside. You think "Apple with worms is mine". When you destroy the worms, do you have an apple with worms inside? No. Can some other worms return into the apple? Yes. When you destroy the apple that you're so dearly clinging onto it, do you have an apple with worms? No. Can some other worms return into the apple? No, because there is no apple. Thus, you let go of the clinging onto the apple and by letting go of clinging, you let go of the apple.
In the same way as clinging onto an "apple with worms", you're holding onto the idea of "self with understanding is mine". You're thinking "Understanding is mine". Now I ask you: When you destroy the 5 skandhas, do you have the 5 skandhas? No. Can some skandha return into that understanding of yours? Yes. When you destroy the understanding that you're so dearly holding onto it, do you have understanding? No. Can some skandha return into the understanding? No, because there is no understanding. Thus, you let go of the clinging onto the understanding and by letting go of clinging, you let go of the understanding.
Just like worms in an apple, understanding is a disease, understanding is suffering, understanding should be let go of. This is how a noble one should see understanding: not mine. Thus, he should not hold onto it.
But now you think again "If there is no understanding, there is ignorance". Again you're thinking like this because you're holding onto the idea of self. In this case you're again holding onto the idea "Understanding is self". You're holding onto this idea because you're holding onto one or more or a combination of these ideas: "Self exists", "Self does not exist".
This is how a noble one should see understanding: not mine.
But now you think "If when there is no understanding, there is no ignorance, then there is wisdom.". You're thinking like this because you're holding onto the idea of self. In this case you're holding onto the idea "Wisdom is self". You're holding onto this idea because you're holding onto one or more or a combination of these ideas: "Self exists", "Self does not exist".
This is how a noble one should see wisdom: not mine.
But now you think "If when there is no understanding, there is no ignorance, there is no wisdom, then there is something." ...
Again, this is how a noble one should see something/anything/ALL: not mine.
You should let go of ALL ideas. Even of the idea "Self does not exist". In this question you can see the Buddha talking about this "letting go of all ideas": Why is "I have no self" a wrong view?
It's because you haven't experienced anatta in its entirety that you're still holding onto ideas about self. Read answers to this question to get ideas how to experience anatta: Can anyone explain non-self or Anatta of Buddhism in simple terms with example?

user8238: Understanding the dharma is certainly conditional and impermanent. If your wisdom was permanent, you could never have gained insights or wisdom from ignorance in the first place!
So your question might be, what use is gaining wisdom if it's impermanent? Wouldn't I lose it all in the end? That would be a form of nihilistic thinking. Wisdom will certainly last long enough to be useful. And indeed, having wisdom will mean that you will take the necessary precautions to prevent yourself from losing wisdom, it means that you must continue to practice to maintain your wisdom, that you should avoid self destructive behavior such as intoxicants and violating precepts to causes ignorance to arise.
A table is impermanent, there's is no 'essence' of the table in the wood/metal. The table is made up of it's parts - legs, surface and so on, and is configured as a table through causes and conditions. However, a table is still useful for putting things on. And a table that is taken care of will last for quite a while. And if you know how to attain wisdom (through the Noble Eightfold Path), you will be able to regain it even if it's lost. Even a murderer like Angulimala became enlightened after he repented his sins.
There is some metaphysical discussion made here about how one can 'uproot' ignorance permanently. However from a Mahayana perspective, even the end of ignorance is empty, that is, the absence of ignorance is also caused and conditioned, impermanent and selfless too. Knowing this, one applies and maintain wisdom as far as one can, and even when one loses it, find the way back into wisdom.

user-1: At least yes, the Dhamma as a stand, or "my" understanding of Dhamma, all stands/views (diṭṭhī) have to be abounded at least, whereas the Dhamma (teching), the raft, will be abounded when having reached the other shore, see the "raft - simile". Note that it is the very last, and in no way good to abound fist or in the middle of the ozean.
Having layed down all views, seeing knowing as unreal as well, one then might reach what is called paññā-vimutti knowing-release, where all kinds of stands or views are abounded, would no more related to.
The word under-stand-ing it self shows well that it is a matter of "holding on it" (upādāna), yet there are Dhammas, there is a Dhamma, that is useable to get free of unreal, insecure (anicca) things.
The first step here is to distinguishing right understanding from wrong understanding: Micchatta Sutta: Wrongness, and after having developed the path completely, one, by abounding it also, gets free of troubles: 

Among those who live above confrontation
      not pitting view against view,
      whom would you gain as opponent, Pasura,
  among those here
  who are grasping no more?
To Pasura

[Note: This is a gift of Dhamma, not meant for commercial purpose or other kinds of low wordily gains by means of trade and exchange]

11541: <p>Buddha says all phenomenon are nonself. If understanding is a phenomenon then my understanding of Dhamma will fade away and I will again fall into ignorance.
So my question is: is understanding a phenomenon?</p>
 111: <p>Understanding is caused. Understanding cannot be gained at will. Otherwise we wouldn't have to study, meditate or cultivate the mind. Understanding in reality means a thought or a sequence of thoughts. Thoughts arise and fall all the time. But once you uproot a defilement, it cannot be associated with thoughts again. Once you uproot ignorance, it cannot be associated with subsequent thoughts.     </p>
 5000: <blockquote>
  <p>"Is understanding a phenomenon?"</p>
</blockquote>

<p>Yes.</p>

<p>Now you're thinking: "When understanding ceases, I'll fall again into ignorance".</p>

<p>No, no my friend.</p>

<p>Now you're thinking why?</p>

<p>Because: when all phenomena cease, there is no ignorance. Think about it ... How could there be ignorance, if all phenomena ceased?? When all ceases, there is nothing that can be ignorant.</p>

<p>Ignorance is like clinging onto an apple with worms inside. You think "Apple with worms is mine". When you destroy the worms, do you have an apple with worms inside? No. Can some other worms return into the apple? Yes. When you destroy the apple that you're so dearly clinging onto it, do you have an apple with worms? No. Can some other worms return into the apple? No, because there is no apple. Thus, you let go of the clinging onto the apple and by letting go of clinging, you let go of the apple.</p>

<p>In the same way as clinging onto an "apple with worms", you're holding onto the idea of "self with understanding is mine". You're thinking "Understanding is mine". Now I ask you: When you destroy the 5 skandhas, do you have the 5 skandhas? No. Can some skandha return into that understanding of yours? Yes. When you destroy the understanding that you're so dearly holding onto it, do you have understanding? No. Can some skandha return into the understanding? No, because there is no understanding. Thus, you let go of the clinging onto the understanding and by letting go of clinging, you let go of the understanding.</p>

<p>Just like worms in an apple, understanding is a disease, understanding is suffering, understanding should be let go of. This is how a noble one should see understanding: not mine. Thus, he should not hold onto it.</p>

<p>But now you think again "If there is no understanding, there is ignorance". Again you're thinking like this because you're holding onto the idea of self. In this case you're again holding onto the idea "Understanding is self". You're holding onto this idea because you're holding onto one or more or a combination of these ideas: "Self exists", "Self does not exist".</p>

<p>This is how a noble one should see understanding: not mine.</p>

<p>But now you think "If when there is no understanding, there is no ignorance, then there is wisdom.". You're thinking like this because you're holding onto the idea of self. In this case you're holding onto the idea "Wisdom is self". You're holding onto this idea because you're holding onto one or more or a combination of these ideas: "Self exists", "Self does not exist".</p>

<p>This is how a noble one should see wisdom: not mine.</p>

<p>But now you think "If when there is no understanding, there is no ignorance, there is no wisdom, then there is something." ...</p>

<p>Again, this is how a noble one should see something/anything/ALL: not mine.</p>

<p>You should let go of ALL ideas. Even of the idea "Self does not exist". In this question you can see the Buddha talking about this "letting go of all ideas": <a href="https://buddhism.stackexchange.com/questions/22643/why-is-i-have-no-self-a-wrong-view">Why is &quot;I have no self&quot; a wrong view?</a></p>

<p>It's because you haven't experienced anatta in its entirety that you're still holding onto ideas about self. Read answers to this question to get ideas how to experience anatta: <a href="https://buddhism.stackexchange.com/questions/22646/can-anyone-explain-non-self-or-anatta-of-buddhism-in-simple-terms-with-example">Can anyone explain non-self or Anatta of Buddhism in simple terms with example?</a></p>
 8238: <p>Understanding the dharma is certainly conditional and impermanent. If your wisdom was permanent, you could never have gained insights or wisdom from ignorance in the first place!</p>

<p>So your question might be, what use is gaining wisdom if it's impermanent? Wouldn't I lose it all in the end? That would be a form of nihilistic thinking. Wisdom will certainly last long enough to be useful. And indeed, having wisdom will mean that you will take the necessary precautions to prevent yourself from losing wisdom, it means that you must continue to practice to maintain your wisdom, that you should avoid self destructive behavior such as intoxicants and violating precepts to causes ignorance to arise.</p>

<p>A table is impermanent, there's is no 'essence' of the table in the wood/metal. The table is made up of it's parts - legs, surface and so on, and is configured as a table through causes and conditions. However, a table is still useful for putting things on. And a table that is taken care of will last for quite a while. And if you know how to attain wisdom (through the Noble Eightfold Path), you will be able to regain it even if it's lost. Even a murderer like Angulimala became enlightened after he repented his sins.</p>

<p>There is some metaphysical discussion made here about how one can 'uproot' ignorance permanently. However from a Mahayana perspective, even the end of ignorance is empty, that is, the absence of ignorance is also caused and conditioned, impermanent and selfless too. Knowing this, one applies and maintain wisdom as far as one can, and even when one loses it, find the way back into wisdom.</p>
 -1: <p>At least yes, the Dhamma as a stand, or "my" under<em>stand</em>ing of Dhamma, all stands/views (<em>diṭṭhī</em>) have to be abounded at least, whereas the Dhamma (teching), the raft, will be abounded when having reached the other shore, see the "<a href="http://zugangzureinsicht.org/html/tipitaka/mn/mn.022.than_en.html" rel="nofollow noreferrer">raft - simile</a>". Note that it is the very last, and in no way good to abound fist or in the middle of the ozean.</p>

<p>Having layed down all views, seeing knowing as unreal as well, one then might reach what is called <em>paññā-vimutti</em> knowing-release, where all kinds of stands or views are abounded, would no more related to.</p>

<p>The word <em>under-stand-ing</em> it self shows well that it is a matter of "holding on it" (<em>upādāna</em>), yet there are Dhammas, there is a Dhamma, that is useable to get free of unreal, insecure (anicca) things.</p>

<p>The first step here is to distinguishing right understanding from wrong understanding: <a href="http://www.zugangzureinsicht.org/html/tipitaka/an/an10/an10.103.than_en.html" rel="nofollow noreferrer">Micchatta Sutta: Wrongness</a>, and after having developed the path completely, one, by abounding it also, gets free of troubles: </p>

<blockquote>
  <p><code>Among those who live above confrontation
      not pitting view against view,
      whom would you gain as opponent, Pasura,
  among those here
  who are grasping no more?</code></p>
  
  <p><a href="http://www.zugangzureinsicht.org/html/tipitaka/kn/snp/snp.4.08.than_en.html" rel="nofollow noreferrer">To Pasura</a></p>
</blockquote>

<p><em>[Note: This is a gift of Dhamma, not meant for commercial purpose or other kinds of low wordily gains by means of trade and exchange]</em></p>
