The accumulation of so enormous a mass of substantial truth is not possible without organization. The faculty for order is just as much a creative one as the faculty for representation. Or they are simply different aspects of one and the same faculty. Out of the truth of countless isolated phenomena there arise the truth of the relationship existing among them: in this way a world is produced.

Hugo von Hofmannstahl

In this age of increasing specification it is comforting to realize that basic physical concepts apply to a wide range of seemingly diverse problems. Progress made in understanding one area may often be applied in many other fields. This is true not only for various fields of materials science but for structure of matter in general. As examples we illustrate how concepts to develop to understand magnetism, superfluid helium and superconductivity have been extended and applied to such diverse fields as nuclear matter, weak and electromagnetic interactions, quark structure of the particles of high energy physics and phases of liquid crystals.

John Bardeen

In this introductory chapter, we shall give a brief overview of condensed matter physics. It begins with a brief r sum of the development of physics in the 20th century, so that we may view condensed matter physics in the context of other branches of physics, and note the important consequences due to the stratification of the physical world into its different layers, each with its quasistable constituent particles and elementary interactions. These make...