This volume deals with fundamental problems of the natural sciences and the philosophy of nature. The issues addressed touch upon the many research areas of Hans Primas, and they reflect both the depth and the breadth of his interests.

Preface -- Instead of a 'Festschrift'; A. Amann, et al. The Primas Effect: On Quanta and Beyond; U. Muller-Herold. Hans Primas and Nuclear Magnetic Resonance; R.R. Ernst. Fragments of an Algebraic Quantum Mechanics Program for Theoretical Chemistry; A. Amann, U. Muller-Herold. Matter. C*- and W*-Algebras of Observables, Their Interpretations, and the Problem of Measurement; A. Amann, H. Atmanspacher. Temporal Nonlocality; G. Mahler. Macroscopic Purification of States by Interactions; H. Narnhofer, W. Thirring. Macroscopic Quantum Phenomena at the SQUID; A. Rieckers. The Geometry of Quantum Probabilities; K. Gustafson. Probability and Quantum Dynamics; E.C.G. Sudarshan. Perspectives on the Molecular Microworld; D.H. Rouvray. The Science of Matter: Fascination and Limits; C.P. Enz. Mind. Holism; A. Shimony. Concepts of Reality: Primas' Nonstandard Realism; B. d'Espagnat. Relative Onticity; H. Atmanspacher, F. Kronz. Rationalism, Determinism, Freedom; V. Hosle. Cuts and Symbols; W. Just. Reflections on the Foundations of Quantum Theory; C.F. von Weizsacker. Appendices. Publications by Hans Primas (until 1998). List of Contributors. Index.