The best known of Plato's dialogues 'The Republic' applies the principles of philosophy to political affairs. Ostensibly a discussion of the nature of justice, it lays before us Plato's vision of the ideal state, covering a wide range of topics: social, educational, psychological, moral and philosophical. It also includes, in the process, some of Plato's most important writing on the nature of reality and the theory of the "forms". Plato is critical of Athenian democracy, which had been responsible for the execution of his friend and teacher Socrates, and his political ideas, as expressed in 'The Republic', started lines of thought which are still relevant today.