This is a selection of John von Neumann's papers and excerpts from his books that are most characteristic of his activity. The book is organized by the specific subjects - quantum mechanics, ergodic theory, operator algebra, hydrodynamics, economics, computers, science and society. The sections are introduced by short explanatory notes with an emphasis on recent developments based on von Neumann's contributions. An overall picture is provided by Ulam's 1958 memorial lecture. Facsimilae and translations of some of his personal letters and a newly completed bibliography based on von Neumann's...