In Marshall's economic principles, political economics and economics are universal. Therefore, "political economics" can not be understood as a discipline that studies both politics and economy, but can also be called "economics" for short. Marshall's Collection of Economic Theories is an economic masterpiece from the first half of19th century to the end of19th century, which has formed its own unique theoretical system and method and has had a far-reaching impact on the development of modern western economics.

Marshall is a professor at Cambridge University and an undisputed leader in the field of British orthodox economics. His Principles of Economics, published in 1890, is regarded as an epoch-making work as famous as Smith's The Wealth of Nations and Ricardo's Principles of Taxation, which replaced the concept of supply and demand in the classical economic system, emphasized the concept of personal utility in the Anglo-Saxon world (English-speaking countries) and formed the foundation of modern economics.

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Marshall's methodology can be summarized as follows:

1, which not only advocates the abstract method of deducing the theoretical model, but also favors the historical description method. His attitude towards the debate between the historical school and the Austrian school on whether to adopt historical induction or abstract method in economic research is that each method has advantages and disadvantages, so all methods should be properly coordinated and should not be mutually exclusive.

2. Absorbing the viewpoint of evolution, we put forward the continuous principle of "only gradual progress, no mutation" to analyze various commodity phenomena.

3. The quantitative relationship analysis method has more clearly evolved into the marginal increment analysis method, which not only uses it to analyze the value problem, but also extends it to analyze other economic problems, such as the distribution of national income, production, the combination and substitution principle of factors, and the allocation principle of various resources in the production process.

4. The equilibrium in mechanics is introduced into economic analysis, and the static local equilibrium analysis method is established. This method is used to analyze the relationship between opposing economic forces, such as the formation of equilibrium prices. This analysis method laid the foundation of modern microeconomic analysis method.

5. Explain various economic phenomena with mathematical formulas, geometric figures and charts, such as supply table and demand table, supply curve and demand curve, elastic formula, etc.