If you were to permit, I would like to add my opinion on the issue
of Nana Nyayas.
The Tipitaka contains the discourses of the Buddha, before that All
the teachings of the Buddha including his instructions followed an
Oral tradition. The discourses explained the essentials to lead a
disciple to Meditation. The disciple in his meditation, goes through
different mental transformations to attain wisdom and the state of
arahat. These nana are the stages of mental developments that have
to be experienced, not learnt by listening to discourses.
The commentariel instructions were given by the commentators who
were Arahats, that may be the reason why you find details of these
Nana developments in meditation, as commentarial annotations.
with metta,
Hasituppada.
____________________________________________________________________
I practiced Burmese meditation in northern Thailand in order to
gain insight by way of nanas (knowledges). I've searched sutta
to find reference to these (such as Udayabbhaya Nana) and came
up blank. As I understand it, they're shrouded in a bit of
mystery because preconceptions could ruin the experience. Is
this a system developed long after the Buddha? Did he only
allude to it?