Plato was born in Athens around 428 or 427 BCE, the year after the death of Pericles, during the first phase of the Peloponnesian War. His father Ariston traced descent from the early Athenian king Codrus; his mother Perictione belonged to the family of Solon and was the sister of Charmides and cousin of Critias, two figures later linked to the Thirty Tyrants. Plato had two older brothers, Glaucon and Adeimantus, who appear as interlocutors in the Republic, and a sister, Potone. After Ariston's death, Perictione married Pyrilampes, who had served as an Athenian ambassador, and Plato's younger half-brother Antiphon appears in the Parmenides as a narrator.

The family placed him among Athens' intellectual and political elite. Ancient biographies report that he studied music, gymnastics, painting and poetry, and competed in tragic drama before turning to philosophy. The story that the young Plato burned his poems after meeting Socrates belongs to later tradition, but it reflects the ancient view that Socrates redirected his literary talent from tragedy to dialogue. Plato's earliest surviving works centre on Socrates' conversations with young aristocrats, sophists, generals and ordinary Athenians, all circling the question of how one should live.

He entered the circle of Socrates during the last years of the philosopher's life. The exact date is unknown, and Plato was probably not yet twenty when he entered the circle that included Crito, Chaerephon, Euclides, Aristippus and Xenophon. Socrates appears in almost every dialogue and remains the dominant figure of the early works. The historical accuracy of the dialogues varies. The Apology probably preserves the general tone and central arguments of Socrates' defence, but even it is Plato's literary recreation. Other dialogues should not be treated as transcripts of actual conversations.

The political crisis of Athens shaped his life. He belonged to an aristocratic family related to Critias and Charmides, both members of the Thirty Tyrants imposed on Athens by Sparta in 404 BCE. Plato says in the Seventh Letter, if the letter is genuine, that he was at first attracted to the revolution because he hoped it would produce just government. He quickly rejected the regime when he saw lawlessness and violence. The restored democracy executed Socrates in 399 BCE on charges of impiety and corrupting the youth. Plato was about twenty-eight. The event became the defining wound and stimulus of his philosophy.

After Socrates' death Plato left Athens. Later biographies connect him with Euclides at Megara and then with travel to Egypt, Cyrene and southern Italy. The Egyptian journey rests partly on the disputed Letters and cannot be confirmed. More secure is his contact with Pythagorean circles in southern Italy, especially Archytas of Tarentum, the philosopher, mathematician and statesman. Archytas' combination of mathematics and political authority influenced Plato's image of philosophical rule.

The ancient biographical tradition places the first Syracusan journey around 388 or 387 BCE. Plato visited Syracuse, then ruled by Dionysius I, and met Dion, the tyrant's brother-in-law and a future political ally. The story that Plato was sold into slavery and ransomed is late and unreliable, but the meeting with Dion belongs to the core tradition. When Plato returned to Athens, he established the Academy in the grove sacred to Academus, about a mile northwest of the city walls.

The Academy was not a university in the modern institutional sense. It began as a gathering in a house and garden where Plato and his associates taught, wrote, investigated mathematics and discussed politics. Plato's students included Speusippus, Xenocrates, Heraclides of Pontus, Philip of Opus, Eudoxus of Cnidus, Theaetetus, Aristotle and many others. Some were citizens, some foreign students, and at least two women, Lasthenea of Mantinea and Axiothea of Phlius, are reported in later sources to have studied there. Mathematics, astronomy, harmonics and dialectic formed its intellectual centre.

Plato's relation to the Academy and his dialogues remains debated. The dialogues may have been published works for a broad educated audience, while more technical teachings occurred in lectures and seminars. Aristotle reports doctrines, especially the Forms and the doctrine of principles, that are not stated plainly in the dialogues. Ancient later tradition spoke of Plato's unwritten doctrines. No lecture text survives, so the relationship between the published dialogues and Plato's teaching inside the Academy must be reconstructed cautiously.

The second Syracusan journey came in 367 BCE, after the death of Dionysius I. Plato's friend Dion invited him to educate the new ruler, Dionysius II, and turn Syracuse toward just government. Plato arrived with hopes of uniting philosophy and political power. The experiment failed. Dionysius II proved unstable, suspicion divided the court and Dion was exiled. Plato left Syracuse but maintained relations with both men. The third journey, around 361 BCE, attempted another political intervention. It ended in danger, estrangement and failure. Plato returned to Athens and spent his remaining years at the Academy.

He died in 348 or 347 BCE, aged about eighty. The will preserved by Diogenes Laertius names Plato's heirs and directs the disposal of his property. Ancient stories make him die at a wedding banquet, in sleep, or after a young Thracian slave played the flute incorrectly and the dying philosopher pointed out the mistake. The date is more secure than the manner of death. He was buried in the Academy, and Speusippus, his nephew, succeeded him as head of the school.

Plato wrote no treatise and no philosophical textbook. His works are dialogues, with one ancient canon of thirty-five dialogues and thirteen letters arranged into nine tetralogies by Thrasyllus, the learned astrologer of Tiberius. The tetralogies begin with the trial and death of Socrates, move through inquiries into knowledge, language, love, myth and politics, and end with the Laws, Epinomis and Letters. Their order is not chronological. Modern scholars often divide the dialogues into early, middle and late groups based on style, form and philosophical development, but the exact chronology remains uncertain.

The first tetralogy contains Euthyphro, Apology, Crito and Phaedo. Euthyphro shows Socrates awaiting trial while questioning a confident religious expert about piety. The dialogue leaves the definition unsettled and exposes the danger of confusing divine favour with moral knowledge. Apology presents Socrates' defence against the charges of impiety and corrupting the young. He claims to possess human wisdom rather than divine knowledge, describes the Delphic oracle that led him to question others and declares that the unexamined life is not worth living.

Crito depicts Socrates in prison refusing escape because the citizen owes obedience to the laws even when the verdict is unjust. Phaedo gives the account of Socrates' death. The dialogue argues for the immortality of the soul, introduces recollection and the Forms, and ends with Socrates drinking the hemlock calmly while his friends weep. The final scene became one of the defining images of philosophy: reason confronting death without fear.

The second tetralogy contains Cratylus, Theaetetus, Sophist and Statesman. Cratylus asks whether names are natural or conventional and explores the relation between language and reality. Theaetetus investigates knowledge and rejects the definitions that knowledge is perception, true judgement or true judgement with an account. The dialogue ends in aporia, but its examination of perception, memory and false judgement opened the field of epistemology.

Sophist and Statesman form a connected sequence that seeks to define difficult concepts through the method of division. The Sophist examines being, non-being, image, falsehood and the art of the sophist. The Statesman defines the political ruler by weaving together knowledge, law and moderation. Theaetetus, Sophist and Statesman are usually considered late dialogues, although their dramatic structure and philosophical difficulty resist simple classification.

The third tetralogy contains Parmenides, Philebus, Symposium and Phaedrus. Parmenides attacks the theory of Forms, especially the relation between Forms and particulars. The young Socrates defends the theory, and the elderly Parmenides shows its difficulties before offering an immense exercise in abstract dialectic. The dialogue is the great crisis of Platonism and the starting point for later metaphysics.

Philebus asks whether the good life consists of pleasure, wisdom or a mixture. Plato argues that pleasure requires measure, intelligence and truth. Symposium presents a series of speeches on love at Agathon's party, from Phaedrus, Pausanias, Eryximachus, Aristophanes, Agathon and Socrates to the drunken entrance of Alcibiades. Socrates reports the teaching of Diotima, who describes love as a ladder from desire for one beautiful body to beauty itself. Phaedrus places love and rhetoric together, presenting Socrates' palinode to love and a critique of written speeches.

The fourth tetralogy contains Alcibiades, Alcibiades II, Hipparchus and Rival Lovers. Alcibiades is a dialogue on self-knowledge and politics whose authenticity is debated. Alcibiades II, Hipparchus and Rival Lovers are generally considered spurious, though useful evidence for the later Socratic tradition. The fifth tetralogy contains Theages, Charmides, Laches and Lysis. Theages is probably spurious. Charmides, Laches and Lysis are early Socratic dialogues on moderation, courage and friendship.

The sixth tetralogy contains Euthydemus, Protagoras, Gorgias and Meno. Euthydemus shows two sophists using eristic tricks to trap a young man, contrasting apparent wisdom with philosophical seriousness. Protagoras stages a debate between Socrates and the great sophist about whether virtue can be taught. Gorgias presents arguments with Polus and Callicles about rhetoric, justice, pleasure and the worth of the philosophical life. Meno asks whether virtue is teachable and introduces the doctrine of recollection through Socrates' questioning of a slave boy.

The seventh tetralogy contains Hippias Major, Hippias Minor, Ion and Menexenus. Hippias Major is now widely accepted as authentic, though it was once doubted. It asks what the fine or beautiful is and ends in aporia. Hippias Minor examines whether the voluntary wrongdoer is better than the involuntary one. Ion presents a rhapsode who claims inspiration but cannot explain the art of poetry. Menexenus parodies funeral oratory and has sometimes been doubted but is generally accepted.

The eighth tetralogy contains Clitophon, Republic, Timaeus and Critias. Clitophon criticises Socratic elenchus from within the Socratic circle and is probably a genuine or early Academic work, though its authorship is disputed. Republic is Plato's longest and most influential political dialogue. It asks what justice is and expands the question into an inquiry into the soul, education, poetry, gender, tyranny and the ideal city. The philosopher-king rules not because philosophy is power but because political power requires knowledge of the Good.

Republic's central images shape the work: the ring of Gyges, the divided line, the cave, the ship of state and the myth of Er. The cave presents prisoners who mistake shadows for reality until one ascends to the sunlight of the Good. The divided line distinguishes image, belief, reasoning and understanding. The myth of Er ends the dialogue with rewards and punishments, reincarnation and the choice of lives. Republic is both a political programme and a study of the philosopher's inner life.

Timaeus gives Plato's most influential cosmology. The dialogue describes a divine craftsman or demiurge imposing order on pre-existent matter according to the eternal Forms. It explains the creation of the world soul, the elements, time, the planets, human beings and the diseases of body and soul. Critias continues the discussion with the unfinished story of Atlantis and ancient Athens. The Atlantis myth frames a struggle between ideal Athens and the wealthy island empire and breaks off before its conclusion.

The ninth tetralogy contains Minos, Laws, Epinomis and the Letters. Minos is generally spurious. Laws is Plato's longest work and presents an ideal city ruled by law rather than philosopher-kings. The dialogue covers legislation, property, education, religion, marriage, punishment and nocturnal council. The Athenian Stranger replaces Socrates as the principal speaker. Epinomis, an appendix to Laws, is attributed in antiquity to Philip of Opus and is generally not by Plato. The thirteen Letters form a collection whose authenticity is widely doubted. The Seventh Letter is the most important because it presents Plato's Sicilian experiences and philosophical reflections, but no letter commands universal acceptance.

The ancient corpus also contains works that were already considered spurious or unassigned to Plato. These include the Definitions, an Academic collection; Demodocus; Sisyphus; Halcyon; Eryxias; Axiochus; On Justice and On Virtue. Around thirty epigrams also survive under Plato's name, but almost all are doubted. They should be distinguished from the dialogues and treated as the pseudo-Platonic tradition. The spurious works are not necessarily worthless forgeries. Several come from the Academy or the Socratic milieu and preserve material about fourth-century philosophy.

Plato's philosophy is therefore known primarily through the dialogues, not through a technical treatise. The early dialogues ask ethical questions through elenchus: What is piety? What is courage? What is moderation? What is friendship? Can virtue be taught? Their characteristic ending is aporia, the recognition that the interlocutor's confident answers have failed. Socrates' irony is not simple mockery. It exposes the difference between possessing an opinion and knowing what one claims to know.

The middle dialogues move from ethical inquiry to metaphysics and epistemology. The Forms become the eternal, unchanging objects of knowledge. Beautiful things participate in Beauty; just actions participate in Justice; the Good stands above the other Forms as the source of being and knowledge. Recollection explains how the soul can know what the senses cannot grasp. Immortality is argued through the affinity of the soul with the Forms and through the doctrine of opposites.

The late dialogues subject the Forms and knowledge to new scrutiny. Parmenides raises objections that remained fundamental to later philosophy. Theaetetus dismantles definitions of knowledge without replacing them. Sophist revises the account of being and non-being, while Statesman revises political theory. Philebus integrates pleasure into a measured good. Laws replaces ideal guardianship with laws, institutions and habits. Timaeus gives a mathematical cosmology. Critias dramatises the fragility of ideal states.

The developmental reading of Plato must be used with care. It helps explain the movement from aporetic dialogue to constructive metaphysics and the stylistic differences between works. Yet Plato may have revised and circulated dialogues over long periods. Some works combine early and late features. Speeches may express positions Plato tests rather than endorses. The dialogues are dramas, and the character Socrates is not a transparent mouthpiece in every passage.

Plato's ethics and politics spring from the soul. In Republic justice in the city mirrors justice in the individual. The rational, spirited and appetitive parts must be ordered by reason. Virtue is knowledge in the sense that the soul must grasp the Good before it can act well. Vice is ignorance or disorder, and punishment aims at correction rather than revenge. The philosopher's detachment from wealth and honour becomes the model for political education.

His treatment of poetry and art is similarly double. Plato excludes most epic and tragic poetry from his ideal city because imitation distances the audience from truth and stirs the passions. He criticises Homer for misrepresenting the gods. Yet Plato himself is one of the greatest literary artists of Greece. His dialogues use myth, poetry, humour and drama to create a form of writing that does what plain exposition cannot. The critique of imitation comes from within a work of supreme imitation.

Plato's influence began with his students. Speusippus and Xenocrates preserved the Academy after his death. Aristotle studied with Plato for about twenty years and developed his own philosophy through criticism of the Forms. The Hellenistic schools rejected or transformed Platonism, but Plato's dialogues remained central. Middle Platonists organised their teaching around selected works, especially Alcibiades, Phaedo, Symposium, Phaedrus, Republic, Timaeus and Parmenides. Plotinus transformed Plato into Neoplatonism. Proclus wrote immense commentaries on the Parmenides, Republic and Timaeus.

Latin Christianity knew Plato through Cicero, Augustine and the translation of Timaeus by Calcidius. Augustine found in Plato a philosophy of eternal truth that prepared him for Christianity. Boethius transmitted Platonic logic and metaphysics into the Latin West. Medieval readers knew only a few dialogues in Latin, with Timaeus serving as the principal text of Platonic cosmology. Plato's reputation as the divine philosopher survived even when his texts were inaccessible.

The Byzantine world preserved Plato in Greek manuscripts. The oldest surviving complete manuscripts date from the ninth and tenth centuries CE, including the Clarke manuscript copied for Arethas and the Paris manuscript that preserves the final tetralogies. More than two hundred medieval manuscripts survive. Papyri preserve fragments of dialogues, and quotations by Stobaeus, Eusebius, Clement, Iamblichus, Galen and other authors provide evidence for the ancient text.

The Italian Renaissance recovered Plato through Greek manuscripts and Latin translations. Marsilio Ficino translated the complete dialogues into Latin for Cosimo de' Medici and founded the Platonic Academy of Florence. Pico della Mirandola, Bessarion, Nicholas of Cusa and later Renaissance thinkers turned to Plato as an alternative to Aristotle. Raphael's School of Athens places Plato and Aristotle at the centre of philosophy. Plato became a symbol of idealism, mathematics, mysticism and intellectual ascent.

Modern philosophy has continually returned to him. Descartes, Leibniz, Berkeley, Kant, Hegel, Schopenhauer and Whitehead all define themselves in relation to Plato, whether by adoption, revision or rejection. Whitehead's famous statement that Western philosophy consists of footnotes to Plato exaggerates but captures his range. The Republic has been read as utopia, anti-utopia, totalitarian warning, feminist manifesto, critique of democracy and model of civic education. The cave has become an image for ideology, media, propaganda and enlightenment.

Modern scholarship debates the chronology of the dialogues, the authenticity of the doubtful works, the relation between Plato and Socrates, the status of the Forms, the political interpretation of Republic and Laws, Plato's treatment of women, slavery, tyranny and democracy, and the role of myth in philosophy. Stylometric and computational studies support broad developmental groupings but cannot replace philosophical interpretation. Plato's texts remain open because the dialogue form refuses to close the argument.

The accurate account of his works is precise. Plato's ancient canon contains thirty-five dialogues and thirteen letters. The secure dialogues include the Apology, Crito, Phaedo, Cratylus, Theaetetus, Sophist, Statesman, Parmenides, Philebus, Symposium, Phaedrus, Charmides, Laches, Lysis, Euthydemus, Protagoras, Gorgias, Meno, Republic, Timaeus, Critias and Laws, together with other generally accepted works. Alcibiades, Clitophon, Greater Hippias, Ion, Menexenus and the letters are debated or rejected to varying degrees. Alcibiades II, Hipparchus, Rival Lovers, Theages, Minos and Epinomis are generally rejected. On Justice, On Virtue, Demodocus, Sisyphus, Eryxias, Axiochus, Halcyon, the Definitions and the epigrams belong to the pseudo-Platonic corpus. No separate technical treatise by Plato survives.