Collapse collapse, when the order that held things together gives way, is what Volume 0 is partly preparing us for. Societies can collapse. So can institutions, ecologies, and the chains of knowledge that pass skill and meaning from one generation to the next. Collapse is not always sudden. Sometimes it is slow—a little less each year until one day we notice that the old way is gone. Sometimes it is violent—war, disaster, epidemic. In either case, what was continuous is broken. The links scatter. First, we have to see collapse clearly. We do not have to expect it every day. But we do well to know that it can happen and that when it does, the question is not "Who is to blame?" so much as "What do we do now?" The answer often starts with what is left. Who is still here? What do they still know? What can we still do with our hands and with the materials at hand? Collapse is an end. It is also a beginning—of a different kind of continuity, built from the pieces. This volume does not promise to prevent collapse. It offers tools for what comes after: how to observe, how to infer, how to correct error, how to pass knowledge on without schools, how to trust and record and deliberate together. When we learn those things, we are not only learning for today. We are learning for the day when someone has to start again. What would you try to save or rebuild first if the world you know fell apart?