Based on the observation of economic reality, this book provides for the foundations of a new structure of national payment systems. Specifically, to this end, a rigorous accounting for money transactions, savings, and invested profit is suggested, with a major aim to settle sustainable lending levels. Profit lies at the heart of economic activities. Indeed, companies, from small to large, seek net gains to remunerate shareholders and to increase their assets. Yet, economists are far from sharing a common theory of profit. Using mathematical tools and a discursive approach, this book contributes to the debates in such regard, in the attempt to provide new answers to old economic issues. What is macroeconomic profit? Is there any relationship between wages, lending, and profit? This book is an accesible resource for economists and financial experts as well as global economics students, researchers, academics and historians alike. It will challenge policy-makers and professionals and lead them on a thought-provoking journey through the realm of macroeconomics.