 Ancient philosophers explored the mix between natural and human contributions in the construction of familiar features of the world. They did not, however, theorize much about exactly what people do in order to create the social world. Instead, they wrote of agreements, compacts, conventions, habits, laws, customs, and so on, without paying particular notice to separating these from one another. In the early modern period, theories of these sources broadened considerably, as did the variety of social phenomena being investigated. Approaches developed in the seventeenth and eighteenth centuries include: