Recalling Neither Perception nor Non-Perception for Nimittas In the state known as neither perception nor non-perception, it seems impossible to cognize the relative particulates that allow it to occur as an event, but one can emerge mindfully from its attainment, as is stated in the Anupada Sutta. Hence, there is a beginning and an end to the event. In this way, I can only define it by what is absent rather than what is present - similar to exiting a noisy nightclub and resting in the dead of the night, then entering the nightclub again, taking with me only the memory of the still night.

Sariputta entered &amp; remained in the dimension of neither perception nor non-perception. He emerged mindfully from that attainment.
Anupada Sutta

This leaves a trace-memory of the event that can be recalled, but even that itself is tenuous for two reasons, 1) by its very definition (neither perception nor non-perception) - from beginning to end - its particulates are so subtle, so indistinct that one can not confidently declare &quot;I am emerged in neither perception nor non-percpetion&quot;. 2. The recall itself poses some accuracy issues, that since it is now in the memory, it is open to all sorts of interpretations including how I have chosen to define it here.
In the instance of neither perception nor non-perception, it seems the ability to discern and cognize are nimittas that are absent. Please correct me?
Is it sufficient for the mind to have experienced the presence of neither perception nor non-perception or must it be investigated further?
I'd argue that its largely irrelevant.  The content of meditative experience really has no bearing on ones practice.  The insight that is attained when one emerges from those states is what matters.  The only value of truly deep meditative absorption is that it allows for equally deep vipassana.