Plato's Book I of The Republics presents three fundamental views on justice which are exemplified in Thucydides' On Justice, Power and Human Nature. Justice is illustrated as speaking the paying one's debts, helping one's friends and harming one's enemies, and the advantage of the stronger.

In both their works, Plato and Thucydides write of the view that justice is honoring one's debts. In The Republics, Cephalus asserts that justice is "the truth and giving back what a man has taken from another." In other words, he believes that we should be truthful and pay back our debts to man and the gods. This view of justice is illustrated at the debate in Sparta between the Lacedaemonians, Corinthians and the Athenians. During the Athenians defense, they remind the Lacedaemonians of the battle with Persia. In this conflict, when Persia was defeated, the Athenians claim to have supplied most of...