Political science in the ancient and medieval worlds was closely linked to philosophy and theology. It often consisted of advice for rulers on how to govern justly. Numerous thinkers and scholars advanced the study of politics and government, including (1) Plato (c.427-c.347 bce), one of the greatest western philosophers to write several dialogues about political matters, including The Republic (c. 360 bce), (2) St. Augustine (ce 354-430) to write City of God (419) about the argument for the centrality of salvation to life, even with regard to politics, etc.