A market participant may either be coming from the supply side, hence supplying excess money (in the form of investments) in favor of the demand side; or coming from the demand side, hence demanding excess money (in the form of borrowed equity) in favor of the supply side. This equation originated from Keynesian advocates. The theory explains that a given market may have excess cash; hence the supplier of funds may lend it; and those in need of cash may borrow the funds supplied. Hence, the equation: aggregate savings equals aggregate investments.