In 388 BCE, Plato was nearly forty. He had lived through an oligarchic coup, a democratic restoration, and the execution of his beloved teacher Socrates by a jury of his fellow Athenians. In his youth, Plato seriously contemplated an entry into Athens’ turbulent politics, but he determined that his envisioned reforms of the city’s constitution and educational practices were vanishingly unlikely to be realised. He devoted himself instead to the pursuit of philosophy, but he retained a fundamental concern with politics, ultimately developing perhaps the most famous of all his formulations: that political justice and human happiness require kings to become philosophers or philosophers to become kings. As Plato approached the age of forty, he visited Megara, Egypt, Cyrene, southern Italy, and, most consequentially of all, the Greek-speaking city-state of Syracuse, on the island of Sicily.
In Syracuse, Plato met a powerful and philosophically-minded young man named Dion, the brother-in-law of Syracuse’s decadent and paranoid tyrant, Dionysius I. Dion would become a lifelong friend and correspondent. This connection brought Plato to the inner court of Syracuse’s politics, and it was here that he decided to test his theory that if kings could be made into philosophers – or philosophers into kings – then justice and happiness could flourish at last.