Victor Weisskopf, one of the grand-masters of the communication of modern physics, sometimes criticised that many presentations tend to concentrate on the most recent developments, which does not necessarily lead to a deeper insight. In this spirit, superstring theory or quantum gravity will hardly play a role in this book. Instead, the development of modern physics from the beginning of the quantum era around 1900 to the radical break with classical physics through quantum mechanics, its unification with the special theory of relativity to quantum field theory up to the Standard Model of particle physics, the most comprehensive theory of physics to date, will be outlined. Following Albert Einstein’s motto that one should treat matters as simply as possible but not simpler, we will have to introduce some basic mathematical formalism. The statement of Ernst Mach towards the end of the 19th century that a man without at least a rudimentary education in mathematics and science is only a stranger in this world, is politically completely inappropriate today, but it may serve as an incentive nevertheless.