Socrates spends the last day of his life arguing that the soul is immortal, with friends who keep finding holes in the arguments, and then dies.

The Phaedo is that day. It is also where the theory of Forms first appears as a worked doctrine rather than a suggestion, and the two facts are connected: the arguments for immortality need the Forms, and the Forms get their first serious outing because he needs them.

What it is like to read

About 30,000 words, and harder than the Apology by a distance. A narrated dialogue — Phaedo of Elis telling the story months later to a group at Phlius — so the whole thing arrives at one remove.

His interlocutors are Simmias and Cebes, two young Thebans with Pythagorean training, and the choice is deliberate: the doctrines under discussion were already Pythagorean property, so Plato has Socrates argue them with people disposed to agree and capable of pressing.

Read it for the opening, the objections, and the death. The middle arguments are the least rewarding part and the dialogue survives them.

Four arguments, of uneven quality

Cyclical (69e–72e). Opposites come from opposites — waking from sleeping, hot from cold — so the living come from the dead, which requires souls to persist and return. Weak: it conflates a process reversing with a thing persisting through it.

Recollection (72e–77a). We grasp that two sticks are equal while never encountering anything perfectly equal, so the standard did not come from the senses. The soul must have known it before birth. Better, and it is the argument that drags the Forms onto the stage.

Affinity (78b–80c). The soul is unitary, invisible and like the eternal Forms; the body is composite, visible and like what perishes. By kinship the soul is the sort of thing that lasts. An argument from resemblance, and Plato knows it establishes a likelihood at best.

The final argument (102a–107a). The soul brings life to whatever it occupies, and a thing cannot admit the opposite of what it essentially brings, so the soul cannot admit death. The most technical, and it depends on the theory of Forms holding.

What lifts the dialogue is that Plato puts the strongest objections in himself. Simmias proposes the soul is a harmony of the body's parts, which ends when the instrument is broken. Cebes proposes it might outlast several bodies and still wear out eventually, like a weaver outliving many cloaks. Both are good, both are pressed hard, and Socrates has to reorganize his position around them.

The second sailing

At 96a Socrates gives an intellectual autobiography that is the most consequential passage in the book.

He describes being excited by Anaxagoras' claim that Mind orders everything, and then disappointed to find Anaxagoras explaining things mechanically after all. The complaint is precise: telling you that Socrates' bones and sinews are arranged thus does not explain why he is sitting in prison rather than escaping. The real reason is that he judged it better to stay.

Finding no satisfactory account of causes, he takes a "second sailing" — when the wind fails, you row — and turns to explanation by Forms. Things are beautiful because of Beauty. It is deliberately unambitious as physics, and it is the beginning of the metaphysics that organizes the rest of Plato.

Key passages

  • 64a — those who do philosophy rightly practice nothing but dying and being dead.
  • 66b–67b — the body as prison, philosophy as purification.
  • 72e–76e — the argument from recollection.
  • 78b–80c — the affinity argument, and the soul's kinship to the Forms.
  • 96a–100b — the intellectual autobiography and the second sailing.
  • 115c–118a — the death.

The ending

The hemlock arrives, he drinks it without fuss, he walks until his legs are heavy and then lies down. He covers his face. Near the end he uncovers it to say that they owe a cock to Asclepius and should not forget to pay it — a debt owed for a cure.

What the cure was has been argued over for two thousand years. The obvious reading is that life is the illness. Whether Plato meant it is another matter, and the line is the reason the dialogue is remembered as literature as well as argument.