The most glaring failure of economists is surely their inability to derive a positive labor supply curve. What they have obtained so far is a hybrid one with backward-bending slopes. This book disproves the bend, so that such a supply relation can only be negative, and further reveals how the abnormal supply is flawed. Instead, this book proves that the relation actually describes the negative cross-demand for labor. Subsequently, this book also defines cross-demand relation for capital, and cross-supply relations of output.