This is a work of system-think on why breakthroughs mostly don't sustain. In answer, it recalls mutual learning, by which the exceptional have defied the norms of decline since before humans could write about it. Part 1 shows the mechanics how complex adaptive systems extend order-Hayek's catallaxy. How lean exploits this is unpacked. Part 2 isolates popular fallacies of control that incentivize undoing. Part 3 offers countermeasures-leveled exploration and exploitation in strategy deployment, standard work, and development of employees, products, services, and methods. Lean turns paradigms and routines from holding on, to sustainably moving on. Lean is not just a factory thing. Lessons abound in nature's fractals and adaptations, admin, and history too; from the present back through World War II, the Industrial Revolution, the Reformation, to its roots in the civilizing of Antiquity. Learners mine hard lessons while knowers sadly repeat them. Great sources on catallaxy-Juran, Hayek, Popper, Kuhn, Sproul, Rother, March-have left us rich deposits of distilled experience. Sustain is a trail guide, locating pivotal insights to defy the entropy of abandon-and-revert, in any enterprise that coordinates resources, time, and treasure in the face of varying, alternative uses.