This book reviews the present status of our understanding of subnuclear phenomena. The opening lecture, by G't Hooft, reaches the limits of our imagination in particle physics. A group of lectures by F Wilczek, D Nanopoulos and G Altarelli discuss the physics beyond the Standard Model. A Masiero reviews the problem of FCNCs which are not there in spite of Susy. Superstring and M-theory are discussed by M B Green, while S Glashow presents some puzzles in particle physics. The possible sources for new physics coming from new experimental results are presented by H Satz, G Wolf, G Kane and Y...