The son of Ariston and Perictione, 'A', was born in the year after the death of the great Athenian statesman Pericles. 'A' was an ancient Greek philosopher, a student of Socrates and founder of the Academy, best known as the author of philosophical works of unparalleled influence. His most famous work is 'The Republic', which details a wise society run by a philosopher. Identify 'A' from the following.