This outstanding collection of essays in commemoration of John S. Bell is the result of the "Quantum (Un)speakables" conference organised by the University of Vienna. The title was taken from a famous note written by John Bell during the "Schrödinger Symposium" of 1987. The book leads the reader from the foundations of quantum mechanics to quantum entanglement, quantum cryptography, and quantum information, and is written for all those who need more insight into this new area of physics.||List of Contributors:||Markus Arndt, University of Vienna, Austria|Alain Aspect, Laboratoire Charles Fabry, Orsay, France|Mary Bell, Geneva Switzerland|Reinhold A. Bertlmann, University of Vienna, Austria|John F. Clauser, J.F. Clauser & Assoc., Walnut Creek, CA|John Conway, Princeton University, Princeton, NJ|Artur Ekert, Oxford University, Oxford, UK|Bernard D'Espagnat, University of Paris (Emeritus), Paris France|Edward S. Fry, Texas A&M University, College Station, TX|GianCarlo Ghirardi, University of Trieste, Italy|Nicolas Gisin, University of Geneva, Switzerland|Daniel Greenberger, CCNY, New York, NY|Walter Grimus, University of Vienna, Austria|Beatrix C. Hiesmayr, University of Vienna, Austria|Gerard 't Hooft, University of Utrecht, The Netherlands|Michael Horne, Stonehill College, Easton, MA|Roman Jackiw, MIT, Cambridge, MA|Simon Kochen, Princeton University, Princeton, NJ|Jon Magne Leinaas, University of Oslo, Norway|N. David Mermin, Cornell University, Ithaca, NY|Olaf Nairz, University of Vienna, Austria|Jian-Wei Pan, University of Vienna, Austria|Roger Penrose, Oxford University, Oxford, UK|R. Rajaraman, Jawaharlal Nehru University, New Delhi, India|Helmut Rauch, University of Vienna, Austria|Franco Selleri, University of Bari, Italy|Abner Shimony, Cupertino, CA|Jack Steinberger, CERN, Geneva, Switzerland|Stig Stenholm, Royal Institute of Technology, Stockholm, Sweden|Lev Vaidman, Tel Aviv University, Tel Aviv, Israel|Thomas Walther, Texas A&M University, College Station, TX|Gregor Weihs, University of Vienna, Austria|Andrew Whitaker, Queen's University, Belfast, Northern Ireland|Anton Zeilinger, University of Vienna, Austria|Antonio Zichichi, CERN, Geneva, Switzerland