how do i do a profit and loss statement 1. Industrial age The accounting income maintains the financial capital preservation, namely, the monetary value that only requires the owner to invest is not eroded, the enterprise income exceeds the input value part is the accounting income. Accounting focuses on reporting financial results. The economic benefits insist on physical capital preservation, which can only be confirmed when the actual production capacity of the owner is saved. It is believed that only by maintaining the actual production capacity of the enterprise can the enterprise reproduce smoothly. Physical capital preservation is more meaningful than the income of financial capital preservation, but it is difficult to measure. This refers to the industrial handicraft industry from the feudal society to the early stage of capitalism. In the 16th century to the 17th century, some western countries of the feudal social system to the system of capitalism, capitalist primitive accumulation is accelerated, deprived of farmers' land on a large scale, make cottage industry collapse, sharply to capitalism works system transformation. Industrial handicraft industry is the embryonic form of enterprise. On the basis of introducing marginal concepts and mathematical argumentation, neoclassical has established a formal "perfect" mathematical model for the neoclassical "laissez-faire order" : general equilibrium. The price is the most important independent variable in this model, which can also be called price mechanism. The process of achieving general equilibrium is also a process of social resources guiding the flow of prices, so the price mechanism regulates the allocation of social resources. Including ambulances, fire engines, sanitation vehicles, TV and radio cars, airport operations, municipal construction projects, etc.