Ok, Felix, I did understand correctly ( I hope)
Sorry this is in English, but my speaking abilities in German are very limited.
I can understand most of it though.
As for your purpose problem, I would say make a different purpose for every few groups of chapters, instead of each individual chapter.
That would set a few sort of goals for your mind to set out to accomplish, and you might retain more information in this way.
Hope I could help.
Good luck!
Viel Glück!!!
