
These brief biographies of more than eighty philosophers of ancient Greece were assembled by Diogenes Laërtius in the early third century. He based these on a variety of sources that have since been lost. Because of this, his biographies have become an invaluable source of information on the development of ancient Greek philosophy, and on ancient Greek culture in general. Most of what we know about the lives and otherwise lost doctrines of Zeno the Stoic and Diogenes the Cynic, for example, come from what Diogenes Laërtius preserved in this book. Mourning what else we have lost, Montaigne wrote: “I am very sorry we have not a dozen Laërtii.” Steamy romance, barbed humor, wicked cattiness, tender acts of humanity, jealous feuds, terrible puns, sophistical paradoxes, deathbed deceptions, forgery, and political intrigue … while the philosophers of ancient Greece were developing their remarkable and penetrating philosophies, they were also leading strange and varied lives—at times living out their principles in practice, at other times seeming to defy all principle. Diogenes Laërtius collected as much biographical information as he could find about these ancient sages, and tried to sift through the sometimes contradictory accounts to find the true story.
I'm a big fan of Socratic philosophy, and there's two main sources for this, Xenophon and Plato.
Xenophon's main Socratic work is traditionally titled The Memorabilia and there are two older translations available online, The Memorable Thoughts of Socrates (Henry Morley) and The Memorabilia (H.G. Dakyns). The latter has footnotes and is probably the better translation but the former might be a little easier to read, but they're both pretty old. A good modern option is Conversations of Socrates (Hugh Tredennick/ Robin Waterfield) which includes all of Xenophon's Socratic works (and useful footnotes). My advice is to try and not take the somewhat moralistic tone of Xenophon too seriously.
All of Plato's dialogues that are generally agreed to be authentic are available for free online, per the old but very readable translations of Benjamin Jowett. Everything attributed to Plato is contained in Plato Complete Works (John M. Cooper). Plato Collected Dialogues (Edith Hamilton and Huntington Cairns) has all of the authentic dialogues plus a few others. The Last Days of Socrates (Hugh Tredennick, I think revised by Robin Waterfield) has the four relevant Platonic dialogues (including Apology {"Socrates' Defense"} which might be the best record of things Socrates actually said.)
The Republic is available on the Perseus Tufts website with lots of good footnotes. I happened to have read Allan Bloom's translation and it has lots of good footnotes and interesting observations too, though I think his opinions may have been somewhat outside those of mainstream scholarship.
Also the third century AD/CE Lives and Opinions of Eminent Philosophers (Diogenes Laertius) is interesting and quite readable (though I haven't read all of it) and could serve as a (dated) introduction to ancient Greek philosophy itself.
> One source of the story of Plato being sold into slavery is Lives and Opinions of Eminent Philosophers by Diogenes Laërtius. An English translation is available online [1] on Project Perseus. You can find the full story in Book 3 that discusses the life of Plato.
[0] https://history.stackexchange.com/a/37499
[1] http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%...
Meat in those days was regarded as an expensive luxury.
