Three volumes planned (Survive, Thrive, Expand), but given the overall scope that seems like it's gonna be difficult. The third is very grab-bag because it's "everything else" - there's no end to what could go in there, it's just going to stop at some point if it's going to be published. Prioritizing human-care and sustainability is definitely a good target, and in keeping with the theme. Probably scientific method, schools of thought, etc. would be chapters or single pages - there's a lot to deal with overall.