One of the most famous proponents was Niccolo Machiavelli, best known for his Il Principe (The Prince). Machiavelli held that the sole aim of a prince was to seek power, regardless of religious or ethical concerns. The ancient Greek historian Thucydides, who wrote the History of the Peloponnesian War, is also cited as an intellectual forebearer of realpolitik.
In the "realist school" of Anglo-Saxon Political Science of the late 20th century this term is mostly used as a synonym of power politics. The policy of Realpolitik was introduced to the Nixon White House by Henry Kissinger. In this context, the policy meant dealing with other powerful nations in a practical manner, i.e. diplomacy with the People's Republic of China rather than containment.