During his first European exhibition in 1969, American conceptual and performance artist James Lee Byars (1932-1997) presented three actions, and with them provided a guideline for experiencing his art: viewers had to believe in the reality he was offering. His premise was the less you had to go by, the greater the scope of your imagination. The artist travelled extensively throughout his life, and maintained his extensive international network by writing letters. Starting from his correspondence with Flor Bex, Lieve De Deyne, and Wies Smals, this Boijmans Study recounts Byars's activities in the Netherlands and Belgium, and also recounts his formative years in Japan.