Jean Tinguely, from 1973 on, started addressing his letter collages to the conductor Paul Sacher. They join the long series of letters to his wife Maja Sacher, a patron of contemporary art, and bear witness to the warm and eventful nature of their friendship over the years. The letter drawings reflect Sacher's interest in Jean Tinguely's work and the phases and intensity of their friendship, and they also provide an insight into the beginnings of the Jean Tinguely Museum in Basel. The important part played by Paul Sacher in the creation of the museum is evident from the letter collages. Letters to Pierre Boulez and Fritz Gerber are also among the collection. A small selection of Niki de Saint Phalle's letter drawings to Paul Sacher provide an insight into the troubled period following Tinguely's death, and Paul Sacher himself contributes some autobiographical notes which constitute a unique document.