I have read accounts that it is possible to experience different types of fruitions from previous cycles. Is there a categorization of all the kinds of fruitions, and a systematic way of re-exploring them?

There are a few kinds of things which I am tentatively labeling as "fruitions".

First, if I focus on the unpleasantness of sensations or if I apply a lot of pressure, especially in jhana, I experience a *blink* followed by a surge of energy. It most naturally happens after a build-up of energy in the third eye area or across the brow. If I try to do it on more diffuse spaces, it tends to cause the second type that I'm going to mention.

It is also possible to induce a sort of fluttering in which attention repeatedly turns sharply back towards "I", which for some reason allows energy to be released. It feels good and even feels orgasmic if concentration is strong. Allowing my eyelids to flutter has this effect.

Third, every so often I will be in a tranquil state of mind and having what feels like a pleasant thought, and then *blip* it is gone, and I can't remember what the thought was. The thought tends to be some combination of 3-dimensional, dynamically fractal, and profound. Unlike the other two, this one feels unpleasant, and I can't induce it at will. This one I'm particularly interested in, because there is lots of variation and it feels important. It's very frustrating not being able to remember afterwards.

Fourth, sometimes when I am napping, nodding off during meditation, or trying to sleep, I will find myself suddenly snapping out of something unknown, with no memory of what was going on during or before. I am unable to induce this willfully.

The third and fourth occur in clusters, so I think it probably has to do with review cycles, but I'm not sure because my awareness of nanas is poor.