The study of economics over time inevitably touches on monetary economics, with particular reference to macroeconomics, or the study of the structures and behavior within an economic system as a whole. Monetary economics focuses on such areas as currency, money supply, debt, pricing and interest rates at the level of citizens and at government level on topics such as fiscal policy, banking and financial sector regulation. Studying these issues from a historical angle reveals the underlying reasons for the systems currently in place within world economies.
The theoretical notion of property has been a major issue in economic theory throughout the ages. Concepts largely unquestioned by many modern societies, property and ownership are ideas that have evolved over time. Aristotle's writings touched on the idea of property, originating notions of private and "common," or public, with regard to property and wealth. Much later, in the 17th century, John Locke explored concepts of property with relation to societal rights and responsibilities.
Economics can seldom be considered separately from society, and economic theories have always tended to coincide with larger political theories. Economics is such a major element in social structure that many of the most notable economic thinkers have also been social theorists. John Locke's philosophies linked economic theory to social structure, connecting property and wealth to the rights and freedoms of individuals. Both Locke and Adam Smith drew conclusions about the value of services or goods as being determined by the amount of labor used to generate them.
Modern economic theory reserves a significant role for business, particularly within capitalist contexts. Early economic theory relating to business generally referred to the merchant trades of the day. Adam Smith's economics approached a more thorough analysis of the role of business within national and global markets, as well as how this relates to social issues such as liberties, labor and capital.
Economic theories often have relation to philosophical theories, in some cases the connection being more apparent than in others. Most of the early economic theorists were philosophers although a more recent example in which both areas of study were combined is in the case of Karl Marx. With communism, philosophy, economics and history are all regarded within the same set of theories, particularly with the Marxist analysis of capitalism.