The article explores how the modern theory of general equilibrium can be expanded to include concepts like increasing returns and monopolistic competition. It aims to show that competitive balance can exist even when there are external factors causing returns to increase. The researchers use mathematical techniques like measure theory and Banach space theory to prove their points. The key findings include the existence of competitive balance in dynamic economies with increasing returns and in monopolistically competitive markets with high setup costs. The article emphasizes the historical importance of these mathematical tools in solving real-world economic problems.