On the one hand, he analyzed in detail how division of labor leads to the improvement of workers' skills, time saving and technological progress, and then examined the conditions for the development of division of labor, putting forward the famous argument that "division of labor is limited by market size"; On the one hand, it examines the decisive role of population growth and capital accumulation on the amount of productive employment, as well as the source of capital accumulation - thrift and savings. These views were regarded as classics by later economists.