Verse 26 is an obvious reference to the topic of verse 15. Where verse 15 merely states that there will be a time when Satan has no more power over the hearts of men, verse 26 makes clear the way in which this "binding" of Satan will occur. Rather than an overt divine intervention, it will be the quiet divine intervention in the hearts and souls of men that will so change to for righteousness that Satan will have no more power, and will thus be "bound".