Hey Nina!, long time no see.

Just complementing your comment to Karen:

> K: Is neutral feeling really exists or it is neutral when
> > there is some form of ignorance (the underlying tendency of
> > adukkhamasukhaa is ignorance)? Is the fourth jhaana has a neutral
> > vedanaa as its characteristic?
> ------
> N: There is feeling accompanying each citta. Also when it seems that there
> is no feeling, such as when seeing arises, there is indifferent feeling. We
> notice pleasant and unpleasant feeling, but we are ignorant of indifferent
> feeling. It is difficult to know its characteristic.
> Indifferent feeling can be kusala, akusala, vipaaka or kiriya.
> The citta rooted in ignorance is always accompanied by indifferent feeling.
> When there is not happy feeling nor unhappy feeling we should not think that
> the citta is kusala. It may be akusala citta rooted in ignorance.
> When indifferent feeling accompanies jhanacitta of the fourth stage it is
> kusala and very pure.

MN 44: Cula-vedalla Sutta
The Shorter Set of Questions-and-Answers

http://www.accesstoinsight.org/canon/sutta/majjhima/mn-044-tb0.html
"Neither-pleasant-nor-painful feeling is pleasant in occurring
together with knowledge, and painful in occurring without knowledge."

[...]

"What obsession gets obsessed with neither-pleasant-nor-painful feeling?"

[...]

"Ignorance-obsession gets obsessed with neither-pleasant-nor-painful feeling."

[...]

"There is the case where a monk, with the abandoning of pleasure &
pain — as with the earlier disappearance of elation & distress —
enters & remains in the fourth jhana: purity of equanimity &
mindfulness, neither pleasure nor pain. With that he abandons
ignorance. No ignorance-obsession gets obsessed there."


Greetings,
--
Hugo