Plato was an ancient Greek philosopher born in Athens in 427 BC. He was the student of Socrates and the teacher of Aristotle. Together these three philosophers are seen as the founders of Western philosophy as practiced today. Plato is best known for his dialogues and the Theory of Forms, which pose the questions “What is Beauty?” “What is the Good?” and “What is Justice?” His masterpiece the Republic has perhaps been the most well read work of philosophy of all time. Plato is famous for his understanding of justice and the ideal state, the allegory of the cave, and the concept of the philosopher king. His dialogues are an excellent starting point for anyone interested in questions like what can we know (epistemology), what’s the best way to live one’s life (ethics), what is the best form of government (politics), what is the nature of reality (metaphysics) and more.

Plato came from an aristocratic family and it seemed that he was destined for politics. Like many Athenian youth at the time, he became a devoted follower of Socrates. Plato would witness two events which would turn him away from politics. First, he witnessed the rise of a brutal regime known as the Thirty Tyrants in his hometown of Athens. Second, he would see his teacher Socrates unjustly murdered by his fellow citizens on charges of “corrupting the youth.” Plato decided to become a philosopher, one who searches for truth. He traveled to Egypt and Italy, and upon returning to Athens founded one of the first schools of higher learning in the West, the Academy.

In the Academy, Plato and other philosophers would discuss topics such as beauty, justice, truth, knowledge and the Good. They would engage each other in philosophical debate, similar to the way Socrates would confront others in Plato’s dialogues. In the dialogues, Plato famously poses a series of questions to whoever he is talking in order to make them reevaluate beliefs they had simply assumed were true. This is known as the Socratic Method. Plato was deeply influenced by Socrates, who he considered “the justest man alive.” He was also influenced by the mathematician and philosopher Pythagoras who saw numbers as constituting the fundamental nature of reality. Above the entrance to the Academy it was inscribed “Let no one ignorant of geometry enter here.”

Plato is best known for his Theory of Forms. He believed that everything has a Form. Something beautiful is therefore that which participates in the Form of Beauty. Something just is an instance of Justice. A particular triangle is an example of Triangleness. It is the philosopher who is able to see the Forms, also known as Ideas, and therefore is able to truly understand the things going on around him. For this reason, in the Republic, Plato says that an ideal state would be ruled by philosopher kings, because only they would know what the Good is and what participates in the Form of Justice.

In the Republic, Plato uses his allegory of the cave to explain what most people think is true. In the allegory of the cave, people are depicted as being chained to a wall in a cave. They stare at the shadows of things created by a fire that’s behind them. In this way, they never see what’s really happening, but only the shadows. In this way, Plato believes most people only see shadows of the truth, but the philosopher is like a prisoner who has escaped from the cave and is able to see what really exists in the world. It is up to the philosopher to then enlighten others and free them from their chains. Plato also uses the analogy of the divided line, showing that most people are content with belief and opinion rather than true knowledge.

Plato believed that the soul is immortal and that it is reincarnated in another life form when one dies. He therefore saw learning as simply the process of remembering the Forms which the soul already is aware of from its previous lives. This is known as the Theory of Recollection and is demonstrated in the dialogue Meno where Socrates finds a slave who is able to solve a mathematical puzzle despite never having been taught mathematics. Because of these beliefs, Plato concluded that so long as people are concerned with material things, their souls will remain stuck in this cycle of reincarnation. The philosopher’s soul, as the result of a lifetime spent contemplating the Forms, can be released from this cycle and instead become united with this higher spiritual realm.

Plato’s Republic describes an ideal state ruled by philosopher kings who have knowledge of truth, justice, and the Good. The philosopher kings are an oligarchy (rule by few) and Plato is a famous early critic of democracy. Seeing his teacher as having been put to death wrongly by his fellow citizens (convicted by a jury of 501 individuals), he did not believe that most people know what is in the best interest of the city. Plato’s famous depiction of the accusation against Socrates, his trial, and his death are found in the sequence of dialogues: Euthyphro, Apology, Crito, and Phaedo. Other important dialogues include the Symposium, where Plato discusses the nature of love, and the Timaeus, which describes the nature of the world.

The importance of Plato for the history of Western philosophy cannot be understated. His understanding of the world, referred to as Platonism, would continue in Greece as well as inspire what became known as Neoplatonism. His thoughts received a renewed interest in the Renaissance, and have had a lasting influence on Christian, Jewish and Islamic philosophy. His student Aristotle taught Alexander the Great and came up with a scientific understanding of the world that remained unchanged for two thousand years. The Republic is considered one of the most interesting and important works of all time. In the 20th century, Alfred North Whitehead would famously refer to the entirety of the European philosophical tradition as “consisting of a series of footnotes to Plato,” and it would be difficult to find a philosopher since who has not been influenced by his ideas.