It has happened before in history. Those who think it can’t happen again are out of their minds. In 1200 B.C., worldwide civilization fell into ruin. That is only partially an overstatement. The Americas and Asia were on a separate path, but the Mediterranean complex of civilizations, the “known world,” was all but destroyed. It was laying the foundation of Western Civilization, which is the modern worldwide standard for science, technology, human rights, and self-government — and critically, an enduring monotheistic society. The Bronze Age collapse took about a century, but that is sudden in terms of history. Before 1300...