A growing scientific field saves lives. It’s also rife with controversy.

Cellular biology has already transformed medicine. It’s the science behind treatments like blood transfusions, in vitro fertilization (IVF), and chemotherapy. But as the field continues to develop, it keeps pushing up against one question: What’s a disease — and what’s a desire? In his new book, The Song of the Cell: An Exploration of Medicine and the New Human, Pulitzer Prize–winning author and cancer researcher Siddhartha Mukherjee takes a deep dive into the perils and potential of advancing cellular science. Below are excerpts from his interview with Apple News In Conversation host Shumita Basu.