Prof. Leon Mestel has been an inspiration to many to study the role of magnetism in the Cosmos. To mark the occasion of his retin'ment from the University of Sussex after 43 years in astrophysics, several of his friends and former students decided to hold an advanced research workshop in his honour. NATO agreed to finance this venture which was held at the Institute of Astronomy at Cambridge. The scientific organizing committee was J. Landstreet, D. Lynden-Bell, F. Pacini, M.A. Rud0rman and N.O. Weiss and most leading experts on Cosmical magnetism agreed to come. We are particularly grateful to Lyman Spitzer who, ably helped by his wife Doreen, !!;ave the after dinner addre~s on how the goddess Astrophysica had foreseen Leon's achievements in classical Greek times. Not without regret we decided to maintain the homog0neity of the material and therefore could not cover Leon Mestel's major achievements in non-magnetic astronomy. His work on the cooling of white dwarfs, his understanding that degenerate hydrogen was a nuclear explosive since its pressure was almost independent of temperature and hence, his picture of supernovae, which is now more commonly applied to novae, his seminal understanding of the 'law' of galactic rotation and his work on the non-linear development of t hp anisotropies generated in gravitational collapse.

The Earth's Dynamo.- Solar Coronal Heating by Magnetic Flux Interaction.- Magnetic Energy Dissipation and Coronal Heating by DC Currents.- Magnetic Winds from Stars and Disks.- Mhd Winds and Jets.- Magnetic White Dwarfs.- Ap-Stars: A New Look at Holding and Confining Their Magnetic Fields.- Magnetic Fields and Star Formation.- Spin-Up and Spin-Down Induced Magnetic Field Changes in Neutron Stars.- Gamma-Rays from Pulsar Magnetospheres: Physics of the Process and Effects on Particle Trajectories.- Cosmic-Ray Production of Light Elements in the Early Galaxy.- Replacement Concepts for Turbulent Diffusion of Magnetic Fields in Stars and Galaxies.- The Magnetic Field in the Local Spiral Arms.- Observations of Magnetic Fields in (Nearby) Galaxies.- Origin of the Seed Magnetic Field for a Galactic Dynamo.- Large-Scale Magnetic Field Generation in Galaxies by Dynamo Processes.- Gamma Ray Jets and Black Hole Magnetospheres in Active Galactic Nuclei.- Cosmical Magnetism.- List of Acronyms.