Sutta 14. Posala-manava-puccha Sutta
Translated from the Pali by Thanissaro Bhikkhu.
For free distribution only.
To one who reveals the past
his doubts cut through --
who has gone to the beyond
of all phenomena,
I've come with a question.
I ask the Sakyan about the knowledge
of one devoid of perception of forms,
who has abandoned all the body,
who sees, within and without,
'There is nothing':
How is he
to be led further on?
The Tathagata, knowing directly
all stations of consciousness,
knows for one stationed in them
and the steps leading there.
the origin of nothingness
to be the fetter of delight,
one then sees there clearly.
That's his genuine knowledge --
the brahman who has lived
 Posala's question concerning the knowledge of the person in the dimension of nothingness has a double meaning: He is asking about the Buddha's knowledge about that person, and also what a person in that dimension of attainment should do to develop his/her knowledge even further. The Buddha's answer deals with the question in both its senses.