Diogenes Laertius
The Canon — how an Epicurean decides what is true
Βίοι καὶ γνῶμαι τῶν ἐν φιλοσοφίᾳ εὐδοκιμησάντων 10.29–34 · Diogenes Laertius wrote probably in the third century CE; nothing fixes him closer. The doctrine he summarises is Epicurus's own, from a lost book called the Canon, written at Athens between about 306 and 270 BCE.
Before he copies out Epicurus's three letters, Diogenes Laertius stops to explain how an Epicurean decides whether anything is true. Six sections: the senses are never wrong, because a sensation reports only what struck it; an opinion is true if what we see confirms it and false if what we see contradicts it; and a 'preconception' is the general idea of a thing that lets you recognise it at all. It is the rule book for everything else Epicurus says, and the shortest one in ancient philosophy.
How to read this page — what a person checked, and what the model wrote
The notes beside this text are here so you can read it straight through without stopping to look things up: what the passage assumes you already know, who is named without introduction, when the author is joking, what a social rule cost to break, and where the translator quietly tidied something up.
A language model wrote them, and no specialist has reviewed them. That makes them a companion rather than an authority — useful the way a well-read friend is useful, and wrong now and then in the same way. If you are writing something with a bibliography, cite the translation, named at the foot of this page, and let a note point you at what to check.
The division of labour on this page:
- Checked by a person: the translation, unaltered from the printed book; the source text, from the edition named below; every map dot for a named place, verified by hand against a gazetteer; every quotation, supplied from a hand-built list.
- The model's work: every note, headnote, gloss and piece of background; scene-location pins, which are its judgement and say so; any claim about tone, register or intent — those are arguments rather than facts, and you are free to disagree with them.
Quotations are the one thing the model is never allowed to propose — it may only explain one it has been handed from a hand-verified list, which is why you will see few of them. Spotting an allusion is the most valuable thing a commentary does and the easiest thing to invent convincingly, so that restraint is deliberate and is not going to change.
Spotted something wrong? Tell me — a reader who catches an error is the fastest way this gets better.
Robert Drew Hicks (Q7343637, 1850-1929) translated the Lives for the Loeb Classical Library in 1925, and Perseus serves it under a CC BY-SA licence. The English is plain and close, and it tracks the Greek clause by clause. He renders the Epicurean technical vocabulary inconsistently, which matters more in this book than anywhere else on the site: πρόληψις is 'preconception', πάθη are 'feelings', and Κύριαι Δόξαι are 'Sovran Maxims', an archaism already in 1925 for the book most modern writing calls the Principal Doctrines.