Hahn is one of the outstanding physicists of the second half of the twentieth century. From his original discovery of spin echoes and his demonstration of nuclear free induction decay stem the most important methods of modern nuclear magnetic resonance. The wide impact of these methods inphysics, chemistry, biology, and medicine is fully acknowledged. In addition, his fundamental contributions in nuclear quadruple echo phenomena, level crossing techniques, self induced transparency and laser physics have been of paramount importance. This book has been designed as a tribute to Hahn at his seventieth birthday. The articles present a stimulating, challenging and, perhaps, controversial contribution to the scientific literature which will be read advantageously by students and research workers from the fields of nuclear magneticresonance in physics, chemistry, biochemistry, and medical imaging together with electron spin resonance and laser optics. The contributors include the foremost researchers in magnetic resonance, among them A. Abragam, M. Bloom, R.R. Ernst, R. Freeman, M.P. Klein, P. Mansfield, M. Mehring, W.B. Mims, R.E. Norberg, A. Pines, A.G. Redfield, R.E. Richards, C.P. Slichter, and J.S. Waugh.