First to second path is interesting for a few reasons:
1) On the way to stream entry, things are straightforward, there are the ñanas on the way to first path and that is it, and one rises up and falls back before stream entry, but there is only one territory, so to speak. However, after first path and after the stages of second path (the ñanas that lead to second path) start showing up, there is sort of a fork in the road, or two possibilities for what is happening from a map point of view: one can be Reviewing the old stages of first path, or moving on into the new territory leading to second path, and sorting out which is which can be confusing.
2) Once one crosses the A&P before second path, then one enters the Dark Night of that path, which may be either weaker or stronger as well as shorter or longer than the one(s) one went through to get first path. There is no predicting this. My Dark Nights before second path were quite moderate and relatively quick in comparison to those of first path, not sure why. Others have reported the opposite, with second path Dark Nights kicking their collective butts.
3) From a practice point of view, this mapping gets much more complex and can get fascinating. The traps are:
a) to substitute thoughts of how to get through the ñanas for the actual work of mindful, precise, accepting, clear, complete investigation that actually causes progress at all stages.
b) to substitute thoughts about the maps and map theory for the actual work of practice as above.
c) to regress back to the review stages of first path and go through those, as they are easier and more comfortable than new territory that is one is not proficient in yet, all the while thinking those are progress stages
d) to forget the more immediate point: whatever is happening now are the sensations for investigation.
4) The advantage of second path is the flip side of those traps: one does know now to go through the stages (generally, assuming a technical, map-savvy practitioner) and thus, one need simply learn to do basically the same things for the new stages, and so most find second path substantially easier than first path, as they have done it once and already know it is possible to complete a cycle, as well has having substantially improved knowledge of the territory in general terms and what worked for them regarding getting through it.
5) Beyond all that, simply practice seeing these sensations now as they are with a focus on the There Characteristics: this is they key to the stages of insight, as always.
Helpful?
Let me know if you have any more specific questions and good luck,
Daniel
