This volume presents a selection of more than 400 letters from and to the Dutch physicist and Nobel Prize winner Hendrik Antoon Lorentz (1853-1928), covering the period from 1883 until a few months before his death. The letters included in this volume have been selected according to various criteria, the most important of which is scientific interest. A second criterion has been the availability of letters both from and to Lorentz, so that the reader can follow the scientific exchange between Lorentz and his correspondent. Of such correspondences only a few unimportant items have been omitted, the emphasis always being on scientific interest. The letters are presented in their original language (which for this volume is mainly German, with a few French and English items); a few Dutch drafts are accompanied by English translations. The book's editor, Anne Kox, has prepared a biography of Lorentz, as well as annotations of selected letters. H. A. Lorentz was well-loved and highly respected both in the Netherlands and abroad, and the letters included here involve his correspondence with Max Planck, Albert Einstein, Ludwig Boltzmann, Wilhelm Wien, Arnold Sommerfeld, Henri Poincare, Erhard Schrodinger and many others.