Three years ago today, Dr. Donald Seldin, known as “one of the dominant intellectual forces in American medicine” passed away. UT Southwestern Medical Center experienced an amazing transformation under the leadership and guidance of Dr. Seldin. We recognize and honor his legacy as we celebrate his timeless contributions to medical education in this interview with Dr. Marvin J. Stone, Foundation Trustee. Dr. Stone’s medical memoir “When to Act and When to Refrain” highlights several defining moments that showcase the incredible influence Dr. Seldin had not only on UT Southwestern but the health of our region.