The study explores a model for how economies grow naturally over time, considering factors like physical resources, people's skills, and the variety of goods available. It shows that in developing economies, growth happens in stages: first by building up physical resources, then by developing skills, and ultimately by creating more diverse products through research. The model suggests that the shift to each higher stage of development happens on its own within the economy. This model combines older ideas of economic growth with newer ones to give a broad view of how different factors drive a country's progress from basic to advanced stages.