We have defined the main task of economic analysis as the explanation of the magnitudes of economic quantities. The student will find also that the main part of this, as of most other works on the subject, is concerned with the theory of the determination of prices, wages, interest rates, incomes, and the like. He may well inquire, therefore, in the midst of so much mathematics, whether the first task of economics is not the investigation of wealth, or welfare. Some economists have endeavored to restrict the boundaries of the science to the investigation of those quantities which are numerically measurable. Well-being, under such a restriction, would not be part of economics at all.

p. 7-8 - Economic Analysis, 1941