God, Bad & Ugly
I am (finally) reading Insight Meditation by Joseph Goldstein. It is very good - clear, accurate, humanized.
Almost as a side-note in one of the earlier chapters, he mentions that there is a typical process that many go through in a meditation practice.
First, all sorts of "good" things happen. There is increased clarity, stability, insights, maybe even bliss.
Then, all sorts of "bad" things happen. There may be all sorts of things in ourselves coming up which we would rather not know about or see, all sorts of unpleasantnesses, pain and so on.
Then, we grow tired of it all. It is all content. It is always changing. What's the point in getting too caught up in it? It all takes on an "ugly" character, at least in terms of being caught up in it. And this frees us to start noticing and being interested in what is not changing. What is it that is not changing? What is the ground that all of this is happening within, and maybe as.
This is very similar to the phases outlined by Evelyn Underhill, in her explorations of the Christian mystics. There is illumination (good), dark night of the soul (bad), and then an awakening to unity - to no "I" in Buddhist terminology. To and as the ground which everything happens within and as.
With a stable meditation practice, these phases may be less dramatic than for the Christian mystics, but I am not even sure about that.