Aion, a major work from Jung’s later years, has long been a source of fascination for a wide variety of scholars and thinkers. Here are two substantial commentaries presented by two important writers on Jung’s life and work. Barbara Hannah’s writing is well-paced and thoughtfully planned, scanning the work from beginning to end, bringing many subtle nuances to light. Marie-Louise von Franz’s lively and free-flowing discussion of key sentences in the work is published here for the first time.