The financial crisis of 2007 and the following recession present a major challenge to macroeconomic theory. This text refines and improves mainstream approaches to contribute to a better understanding of the monetary and fiscal policies that have been complicated by low-interest rates and super-expansive monetary policies. A concise treatise on modern macroeconomics that would work well as a text for advanced undergraduates or first-year graduate students in economics... An especially nice feature is that the computer code for the basic model is included in an appendix so that instructors and students may modify the code as they work through the material.