The Republic is arguably Plato's most important work and was written in his middle period, around 370-5 BC. It is a philosophical masterpiece containing acute political theory as well as being great literature, and as such is not easily understood on first acquaintance. It has as its central problem the nature of justice. In a word, what is justice? The central character is said to be Socrates, Plato's own teacher as a young man, whom he had seen tried and executed for his politics and religion. The Republic is an examination of the figure of the philosopher, an examination of metaphysics, and epistemology and is confirmation of Plato's dedication to formulating a society based on eternal ideas of truth, goodness and justice.