The canon of enduring questions

The turning point where Plato subjects the middle-period Forms to their gravest criticism; its baffling second half became, for the Neoplatonists, the supreme metaphysical text in the whole corpus.

Plato's one work of systematic cosmology, and by far his most influential in the Latin Middle Ages — for centuries the only dialogue available in the West, through Calcidius's partial translation.

Form, matter and cause are argued out in the Physics, not here, and the works on animals and the soul are built on the framework it lays down; what this book asks is what it takes for anything to be at all. Alexander of Aphrodisias, Avicenna, Averroes and Aquinas each built a commentary on it.

The physics epitome of Epicurus's system, addressed to a pupil and preserved whole by Diogenes Laertius; it condenses the lost thirty-seven books of On Nature into a single letter.

The only work by Lucretius that survives. Its text rests chiefly on two ninth-century manuscripts now in Leiden: the Oblongus and the Quadratus, named for their shapes.

Finished after the Tusculan Disputations, it opened a run of three books on religion: On Divination and On Fate followed in 44 BCE.

A compilation, not a composition: the recorded sayings and dialogues of Confucius, assembled by disciples over generations and canonized under the Han, and for centuries the first book of the Confucian curriculum.

One of the short definitional dialogues, in which Socrates hunts a single concept — here holiness — and comes away empty-handed; it opens the tetralogy that runs through the trial to the execution.

An early inquiry into a single virtue, pairing naturally with the Charmides on temperance; the question it leaves open — whether courage is really a form of knowledge — points ahead to the Protagoras.

Generally judged spurious — a post-Platonic imitation carried under his name in the corpus — this short exercise on prayer is useful mainly as a specimen of how the school later wrote in Plato's manner.

Plato's fullest dramatic contest between Socratic questioning and sophistic display, staged among the age's leading intellectuals; its question of teachable virtue passes straight into the Meno and Gorgias.

One of the shortest early dialogues, and Plato's only sustained treatment of friendship as such; the questions it cannot answer are the ones Aristotle later organises in the Nicomachean Ethics.

A middle-period masterpiece built as a sequence of set speeches rather than a cross-examination; with the Phaedrus it is Plato's great treatment of erôs, and the source, through Ficino, of the phrase 'Platonic love.'

Classed among the spurious works and doubted since antiquity, this short dialogue on wealth is carried in the corpus under Plato's name but is very unlikely to be his.

A late and technically demanding dialogue on whether pleasure or wisdom makes a life good; its exact place in the late group is unusually uncertain, and it is Plato's fullest ethics of pleasure.

One of three ethical treatises transmitted under Aristotle's name, alongside the Nicomachean Ethics and the Magna Moralia — the last of the three being the one whose authenticity is disputed.

The fullest of Aristotle's ethical treatises, and the one the tradition kept: it shares three books with the Eudemian Ethics, which covers the same ground. Its last page hands the subject over to the Politics.

Not a single work but the gleanings of a lost body of writing: sayings from a medieval Vatican manuscript, quotations left by hostile authors, and text still emerging from the burned papyri of Herculaneum.

The ethical counterpart to the letter to Herodotus: where that letter treats nature, this treats conduct — death, the gods, desire and pleasure — the same four concerns later gathered into the tetrapharmakos, the four-line Epicurean creed.

Qohelet, the speaker, exists only in this book. We hold all twelve chapters, read in the King James English of 1611 without verse numbers; the Hebrew original is not held.

The whole of what survives of him: the teaching of his house of learning in Jerusalem, gathered into one book and signed with his name.

Cicero's fullest treatment of ethics: three conversations, set years apart and in different places, bound into one survey of what the leading schools said a life is for.

The practical sequel to the treatise on the chief good, written next: that book compares what the schools say the good is, and this one puts the answer to work against fear and grief.

Copyists kept this and On Old Age bound together for so long that printers followed them. The edition prints the Dream of Scipio after it, which belongs to De re publica.

The last of his philosophical books, and the one that travelled furthest: for centuries afterwards it was simply the standard book of conduct.

Alone among Plato's works it is a courtroom monologue rather than a dialogue, and with the Euthyphro, Crito and Phaedo it forms the quartet dramatising Socrates' trial and death — the events that turned Plato toward philosophy.

Among the shortest dialogues, and the first place Plato treats poetry as divine possession rather than craft — a theme he takes up again, far more harshly, in the Republic's quarrel with the poets.

Its authenticity is disputed — unquestioned in antiquity, doubted since Schleiermacher — which is now the salient fact about it; the longer of the two Alcibiades dialogues attached to Plato's name.

A pivot in the corpus, standing between the aporetic early dialogues and the middle-period metaphysics: the theory of recollection and the knowledge/true-belief distinction first surface here, on the road to the Phaedo and Republic.

The early companion to the Laches: where that dialogue fails to pin down courage, this one fails to pin down temperance — set just after Socrates' return from Potidaea, among relatives of Plato who became tyrants.

Plato's central inquiry into knowledge, and the first of a late trilogy continued in the Sophist and Statesman; famously it reaches no definition at all, ending in deliberate impasse.

Forty numbered sayings, most no longer than a sentence, that condense Epicurus's ethics into a form his followers could memorize and a scattered school could carry and share.

Readers who wondered why Cicero sided with the sceptical Academy were sent here by On the Nature of the Gods, written later the same year: this is where he defends arguing every side of a question and settling for the probable.

The one book attributed to Sun Tzu, and most of the evidence that he existed. Its thirteen chapters reached later readers through the warlord Cao Cao, who annotated them around 200 CE in the oldest commentary to survive.

The book handed down under Laozi's name is also known as the Daodejing, the Classic of the Way and Virtue. Its two parts are read here complete, in the English translation that James Legge, Oxford's first professor of Chinese, published in 1891.

Set in the prison between the Apology's verdict and the Phaedo's execution, it is the shortest of the four last-days dialogues and the one that turns from Socrates' own fate to the citizen's duty toward the state.

The bridge from the early ethical dialogues to the Republic: its confrontation with Callicles over whether injustice pays sets up the question the Republic devotes its whole length to answering.

Almost entirely a set-piece funeral oration rather than a dialogue; its authenticity is backed by Aristotle's references, and it reads as Plato's deliberately ambiguous parody of Athenian patriotic rhetoric.

The centre of the corpus and the fullest statement of the middle-period philosophy — the Forms, the tripartite soul, the ideal city — gathering into one work the ethical and political threads of the Gorgias, Meno and Phaedo.

An unfinished late dialogue, broken off in mid-sentence and intended as the sequel to the Timaeus; its importance is almost entirely as the ancient origin of the Atlantis story.

The direct sequel to the Sophist, and the corpus's bridge from late metaphysics toward the legislation of the Laws; its claim that expert knowledge outranks written law reconsiders the Republic.

Plato's longest and last dialogue, left unfinished at his death and the only one without Socrates; a practical, law-by-law counterpart to the ideal city of the Republic.

Historians use it as a source rather than as a text to interpret, which is true of nothing else under Aristotle's name. It belongs beside the Politics, as the surviving piece of the survey that fed it.

Not a finished book but lectures, with shorter pieces and marginal notes worked in — and the place where the Nicomachean Ethics was heading when it closed by saying that the study of character runs on into the study of constitutions.

Aristotle treats the same ground himself in the household economics of Politics I. These three books keep their place in his corpus on the strength of the name alone; scholarship removed them without settling on anyone else.

Four volumes of the speeches themselves — some delivered, some, like the case against Verres, only published. The philosophical books that fill the rest of the shelf came later, most of them once he had been shut out of that life.

Plato wrote a Republic and then a Laws; Cicero set out to do both, and the treatise on law is this book's companion — begun a couple of years later and left unfinished.

Unfinished, unpublished, and on the available evidence never released at all. For centuries it travelled as the lesser half of a pair whose better half had gone missing.

A brief, aporetic early piece whose deliberately perverse conclusion has kept it a standing puzzle — and whose authenticity a few scholars still question, though Aristotle already treated it as Plato's.

A comic dialogue framed as Socrates' report to Crito, and the corpus's fullest exhibition of sophistical fallacy — much the same material Aristotle would later systematise in the Sophistical Refutations.

Plato's only dialogue given wholly to language and the correctness of names; hard to date and unusual in the corpus, it stands at the head of a debate the philosophy of language has never closed.

Pairs with the Symposium as Plato's second great study of love, but reaches further — into rhetoric, dialectic and a famous closing critique of writing; unusually, it is set in the countryside outside Athens.

The technical heart of the late trilogy, led by the Eleatic Stranger rather than Socrates; its solution to the puzzle of not-being is Plato's most sustained piece of pure logic and ontology.

The medieval schools came at these six through Porphyry's Isagoge. The rest of the corpus simply uses them: the Physics, the Metaphysics and the biological works take the syllogism and the ten kinds as given.

The published title keeps the quotation marks around Art from Freese's 1926 Loeb edition. Its subject is public life — the assembly, the court, the funeral oration — but its form is the school's, like everything else of his that survives.

The Rhetoric is its nearest neighbour in the corpus: nowhere else does Aristotle take an art apart from the maker's side, and nowhere else does he discuss poetry at any length.

The root text of the Mīmāṃsā school, ascribed by tradition to Jaimini, though the sūtras quote his opinion by name beside other teachers'.

Not the speeches but the account of them, made when the courts had stopped sitting. The edition carries Orator with it, the portrait of the ideal speaker written for the same dedicatee in the same year.

The only book behind this persona, cited here in the King James Version of 1611; the Dialogue speaks as Job the character who challenges divine justice, not as the book's anonymous poet.

The longest and most doctrinally ambitious of the last-days group, and the point where Socrates' conversations give way to Plato's own metaphysics: the theory of Forms stated outright, at the deathbed.