Words the Greeks argued in

Literally: Beginning, origin, the thing that rules.

The first principle everything else comes from and can be explained by. Water for Thales, the boundless for Anaximander, air for Anaximenes. Asking for the archē is asking for one answer that covers the whole of nature, and that demand is roughly where Greek philosophy starts.

Literally: Without limit, without boundary.

Anaximander's candidate for the origin of things: not water or air or any other familiar stuff, but something indefinite, because anything with definite qualities could not give rise to its own opposites. The first recorded move from an observed substance to a theoretical one.

Literally: Word, account, ratio, reasoned speech.

The one word that most reliably changes meaning under you. In Heraclitus it is the pattern the world runs on, which people fail to notice even while living in it. In Stoicism it is the rational order of the cosmos, which human reason is a fragment of. In ordinary argument it is simply the account you give of something.

Literally: Growth, the way a thing turns out when left to itself.

Nature, in the sense of what something is by its own constitution rather than by human arrangement. The contrast with nomos, human convention, powers most Greek argument about law, ethics and justice: is the rule in question written into things, or written by us?

Literally: Custom, law, what is assigned.

What holds because a community has established it rather than because nature requires it. Sophists pressed the point that much of morality is nomos, which is why Plato spends so long trying to show that justice is not merely an agreement among the weak.

Literally: Order, arrangement, ornament. The root of 'cosmetic'.

The universe considered as an ordered whole rather than a heap. Calling the world a kosmos is already a claim: that it has a structure a mind can follow. Pythagoras is credited with the usage, and the Stoics make the ordered whole the thing a good life is lived in agreement with.

Literally: Breath, the thing that leaves when you die.

Soul, but without the later Christian baggage. For Aristotle it is the form of a living body, what makes a thing alive rather than a corpse, so plants have one too. For Plato it is what survives and what philosophy is the care of. Socrates' whole mission is stated as tending to the psychē.

Literally: Mind, the act of noticing.

Intellect, specifically the capacity to grasp something directly rather than by working it out step by step. Anaxagoras made it the cosmic principle that sets matter in order. Aristotle makes it the part of the soul that grasps first principles, which cannot themselves be demonstrated.

Literally: Excellence at being the kind of thing you are.

Usually translated 'virtue', which narrows it too far. A knife has aretē if it cuts well, a horse if it runs well. Human aretē is doing well the thing humans distinctively do, which is why the Greek ethical question is 'what is a human being for?' rather than 'what am I obliged to do?'.

Literally: Having a good daimon, a well-favoured spirit.

The standard translation 'happiness' misleads, because eudaimonia is not a feeling you can have this afternoon. It is a life going well as a whole, judged from the outside as much as the inside, which is why Aristotle can ask whether a man can be called eudaimon before he is dead.

Literally: End, completion, the point at which a thing is finished.

The goal a thing is directed towards, which for Aristotle explains it better than its material does. An acorn's telos is the oak. The modern quarrel with Aristotle is largely a quarrel about whether nature contains ends at all, or whether we read them in.

Literally: Practical good sense.

Knowing what the right thing to do is in this situation, with these people, now. Aristotle separates it sharply from theoretical knowledge: you cannot get it from a book, only from being brought up well and doing it often. It is the virtue that tells the other virtues when to act.

Literally: Standing over something, having it firmly.

Knowledge in the strong sense: not merely holding a true belief but holding it in a way that cannot be shaken, because you can give the account. Plato's insistence that knowledge differs in kind from true opinion is the beginning of epistemology, the field named after this word.

Literally: What seems to be the case. Also reputation.

Opinion or appearance, as against knowledge. Parmenides divides his poem into the way of truth and the way of doxa. Plato treats the world our senses report as the domain of doxa, which can be correct and still not be knowledge, because the holder cannot say why.

Literally: Un-forgetting, un-concealment. The a- is a negative.

Truth, but built in Greek as the removal of a covering rather than the matching of a statement to a fact. Heidegger made a great deal of the etymology; classicists are divided on how much the Greeks heard it. Either way the word sits at the centre of Parmenides' poem.

Literally: Cross-examination, putting to the test.

The Socratic method, described from the inside. Socrates takes a claim his companion is confident about, draws out further beliefs the man also holds, and shows that together they cannot stand. The outcome is usually aporia rather than a doctrine, which is what made him so irritating.

Literally: No way through. A road with no crossing.

The state of being genuinely stuck, having seen that what you believed cannot all be true. Plato treats it as progress rather than failure: the man who knows he is lost is better placed than the man who thinks he has arrived.

Literally: The midwife's craft.

Socrates' own image for what he does. His mother was a midwife; he delivers other people's thoughts and then tests whether the newborn is worth rearing. He insists he has no doctrine to hand over, only the skill of bringing yours into the light.

Literally: Untroubledness. Absence of disturbance.

The goal shared, with different routes, by Epicureans and sceptics. For Epicurus it comes from removing groundless fears, chiefly of the gods and of death. For Pyrrho's followers it arrives unexpectedly once you stop trying to settle questions that cannot be settled.

Literally: Not being acted upon. Freedom from pathē.

Not apathy, and not numbness. The Stoic claim is that the destructive passions rest on false judgements about what is good, so correcting the judgements removes the passion. The sage still feels the good feelings, which the Stoics list separately.

Literally: Pleasure.

The word behind 'hedonism', and the source of the standing misunderstanding of Epicurus. His pleasure is chiefly the absence of pain in the body and disturbance in the mind, reached by bread, water, friendship and moderate wants, not by the banquets his opponents advertised.

Literally: Outrage, violent humiliation of another.

In Athenian law an offence of deliberately shaming someone, and only in the literary sense the pride that provokes the gods. Tragedy turns it into overreaching, and the journal's pages on myth use it in that later sense while noting the legal one.

Literally: Soundness of mind. Being of sound intent.

Temperance or self-command, one of the four cardinal virtues. Plato locates it in the agreement of the parts of the soul about which part should rule, which makes it less a matter of resisting desire than of not being at war with yourself.

Literally: The way things are settled. A judgement, a lawsuit, also a penalty.

Justice, with an older sense of the ordering that keeps each thing in its place, including in nature. Anaximander's one surviving sentence has the elements paying one another penalty for their injustice, which reads the cosmos as a lawcourt.

Literally: Beingness. Also, in everyday Greek, a man's property.

Substance: what a thing fundamentally is, as against the properties it happens to carry. Aristotle's Categories makes it the first category and everything else dependent on it, and the medieval Latin substantia carries the argument into Christian theology.

Literally: Look, shape, what a thing presents to the eye.

Plato's Form: the single thing all beautiful things have in common, existing independently of them, which is why the theory is so hard and so durable. Aristotle keeps the word but brings the form down into the object, where it is the arrangement rather than a separate item.

Literally: A divine power, not necessarily a person and not at all a demon.

Socrates reports a daimonion, a divine sign, which never tells him what to do and only ever stops him. It is one of the charges at his trial, and one of the things about him that no later account has managed to explain away.

Literally: Craft, skill, knowing how to make something.

Expertise of the kind a shipwright or a doctor has: teachable, aimed at a product, and answerable to results. Socrates keeps asking whether virtue is a technē, because if it is, someone should be able to teach it, and he cannot find anyone who can.

Literally: The city, understood as its people rather than its walls.

The unit of Greek political life, small enough that a citizen could know the shape of the whole. Aristotle's claim that a human being is a political animal means something stronger than 'sociable': it means we only reach our full form inside a polis.

Literally: Saying everything. Speaking without holding back.

Frank speech, prized in democratic Athens and dangerous everywhere else. It is the Cynics' signature practice: Diogenes tells Alexander to step out of his light. The speaker takes a risk in saying it, which is what separates parrhēsia from mere rudeness.

Literally: Effort, striving. Latin, not Greek.

Spinoza's term for the tendency of each thing to persist in its own being, which he makes the actual essence of the thing. Desire, on his account, is this striving become conscious of itself, which is how a geometry of substance turns into an account of human emotion.