In conversation about the processes of regeneration and repair of living systems from cells through organisms, from humans to ecosystems with Professor Jane Maienschein, Arizona State University, Director History and Philosophy of Science Project, Marine Biological Laboratory, Woods Hole, Massachusetts, and Dr. Kate MacCord, Assistant Professor, Arizona State University, and Program Director, Marine Biological Laboratory, Woods Hole, about their book 'What is Regeneration?' (University Chicago Press 2022). We explore the development of the idea in biology, its changing meaning, its limits and its transferability across scales from microorganisms in your gut to forest fires and beach restoration, through to applications in sciences of the brain and regenerative medicine for humans.