This is one of the Cambridge school founder Marshalls masterpieces. It is recognized as the landmark in economic circle, casting profound influence on the modern economics development. It introduces the comprehensive basic theories in easy language. The achievement is it establishes the static economics, and provides a common theoretical framework for various micro economic schools. The ""static analysis paradigm"" by Marshall has evolved to be the local equilibrium analysis, the tools of economic analysis, and the price theory proposed by him is still the basic price theory in economics.