The political near-breakdown in Germany marks the beginning of the end for the European experiment, for an era of openness toward refugees and migrants in the West, and for Angela Merkel, the German chancellor at the center of the European political establishment.

Or, perhaps, it is a close call in which Ms. Merkel made difficult sacrifices to hold it all together, as she has done many times before.

Or maybe something in between.

The stakes of what is happening in Germany are difficult to overstate, but it can be easy to lose track of how this came to pass and how to think about what could come next. What follows is a simple guide.