This book—the fruit of a lengthy research project, which has allowed us to gather and organize coherent sets of material that reflect the timeline of René Heyvaert (1928–1984)’s artistic experimentations—aims to show, for the first time, a significant selection of his mail art. His mail art is linked to his generally multiform oeuvre—which retains, given that he was originally an architect, an overt material and spatial relation to its environment—as well as to his vital circumstances: his gradually deteriorating health, and the loneliness that fed his epistolary vocation. [publisher's note]