Mainstream economics has never been more vulnerable to a loss of trust. From liberal economic thought to Keynesian macroeconomic theory, the limitations of the thoughts have become more and more obvious in reality. The most frustrated by the decline in the practical value of the theories are those determined liberals who have tried to modify the old theories. It has been repaired to make up for it in many ways, but it doesn't seem to make sense. Economics needs new ideas. The content of this book is the focus of current economics. What is the theory of debt? The relationship between low or negative interest rates and high debt & inflation? The failure of monetary and fiscal policies? Why does TFP tend to decline? What are the internal factors of economic development and population growth? This book gives a theoretical explanation of these phenomena and problems. It belongs to the frontier research of macroeconomics and has urgent practical needs.