B: Lack of impurities of mind.
A: And what are those impurities ?
B: kAma, krodha, etc.
A: Is it possible to totally eradicate these ?
See story of purANa-s, you will find ample proof.
That’s why shrI-vidyAraNya shows that even jIvanmukta-s are not free of these ashuddhi-s :
yadA tu jalAddravatvaM vahnervoShNatvaM nivAryeta tadA chittAtkarttR^itvAdinivAraNasambhavaH .
Translation by Goodding :
When one can remove fluidity from water, or heat from fire, then there is the possibility of removing the notion of being a doer, etc. from the mind.
A: So, what is this purity which is natural to jIvanmukta-s and is practiced by sAdhaka-s :
B: abhibhava (overcoming) of these impurities to maximum extent. This is done by yoga and sadvAsanAbhyAsa (practicing good qualities).
So, everyone can practice this chitta-shuddhi.
And, clearly there is no thing like 100% chitta-shuddhi.
A: Why should one try to reach this chitta-shuddhi ?
B: For GYAna.
A: Any proof that it is needed for birth of knowledge ? Any shruti, etc. ?
B: vairAgya, etc. are needed for GYAna, because shruti says : shAnto dAnta uparatastitixuH, etc.
A: But, shruti doesn’t say that chitta-shuddhi is for GYAna. It says vairAgya, etc. are needed.
B: It is intermediate state. Chitta-shuddhi happens between vairAgya, etc. and GYAna. Without chitta-shuddhi there can be no GYAna.
vairAgya is itself a type of shuddhi.
A: Be it so. But in first case, we have no specific word for chitta-shuddhi in shruti.
In second case, overcoming falsehood, etc. are needed for saving oneself from sins and gaining trust of others, etc. So, truth which is eradication of falsehood(a type of ashuddhi) is not unique to GYAna. So, you can’t say that any type of chitta-shuddi will work for GYAna.
You must have specific type of shuddhi which is otherwise known as sAdhana-chatuShTaya.
viveka is a type of shuddhi which means overcoming aviveka(indiscrimination of eternal and others)
vairAgya means overcoming rAga in anitya, etc. And so on.
So, it comes that generalized chitta-shuddhi is not the need of GYAna. The specific type of chitta-shuddhi which is needed is well depicted by shruti and AchArya, etc.
Now, what’s the use of karma ?
shruti says that karma-s are needed for GYAna as – yaGYena dAnene tapasAnAshakena.
So, we hold that karma helps in gaining viveka, vairAGYA, guru, etc.
Someone says that karma-s are not unique cause of chitta-shuddhi. That’s true. But, generalized chitta-shuddhi is not essential for GYAna too.