
Euthyphro is one of Plato's early dialogues, dated to after 399 BC. Taking place during the weeks leading up to Socrates' trial, the dialogue features Socrates and Euthyphro, a religious expert also mentioned at Cratylus 396a and 396d, attempting to define piety or holiness. The dialogue is set near the king-archon's court, where the two men encounter each other. They are both there for preliminary hearings before possible trials. The argument of this dialogue is based largely on "definition by division". Socrates goads Euthyphro to offer one definition after another for the word 'piety'. The hope is to use a clear definition as the basis for Euthyphro to teach Socrates the answer to the question, "What is piety?", ostensibly so that Socrates can use this to defend himself against the charge of impiety.
Its fascinating to discover how many thoughts and ideas they had which are still relevant in our societies today. Also, they are incredibly readable, its like taking part in on a conversation among friends.
I wouldn't pick Meditations as being a intro classical philosophy tho, the Stoics were very much their own school of thought, and not the primary one that carried forward into later eras. It's a fascinating school of thought, but more also a diversion in getting up to speed (another great side-path from the same era is Pyrrhonian Skepticism!). Aurelius is also really late chronologically (and frankly not a philosopher at all... The modern equivalent would be a celebrity publishing a self-help book, still an extremely fascinating historical document tho).
I'm a huge fan of the Alan Bloom version of Plato's Republic. But if we're getting specifically into Plato, I'd feel remiss if I didn't mention the Euthyphro too.
There is also a _lot_ to be said in favor of reading the history of philosophy in rough order. It's a conversation through the millennia, and you can't truly understand what an author is saying unless you understand the context they are replying to. Eg. Kant is frankly unintelligible (and subject to wild misinterpretation) unless he is read as a rebuttal to Hume's continuation of Descartes's protect (as Kant himself says in the intro to the first critique).
Re analytic philosophy: In the words of my thesis advisor "breaking philosophy down into the categories of analytic and continental is like breaking down cars into the categories of those-with-four-wheel-drive and those-made-in-Europe".
If you've never read Plato before, I'd suggest not to start with the Republic — it is diving into the deep end of Plato. I'm saying this as someone who has recently completed Republic[1], and thoroughly enjoyed it (and fumed at it in some places).
Instead, get familiar with some of the earlier, and famous, Socratic dialogues: Euthyphro, Apology (this is referring to a "formal defense", i.e. apologia; not regret), Crito, et al — they're shorter, give you a great flavour of Socrates, and will prepare you for the Republic. An excellent English translation here is the Five Dialogues[2], a fine selection by Hackett Publishing. I'm happy that I started with this.
[1] There are many English translations; I'll strongly recommend the "Reeve Edition". This translation recasts the entire dialogue as direct speech, this makes it easy to keep track of the speakers. Ensure it is this Reeve-only edition (because Reeve also revised an earlier translation by Grube): https://www.hackettpublishing.com/republic
It’s a great place to start.
I enjoyed Camus due to it being an attempt to move beyond Nietzsche and offer something more digestible, but I never moved past the Nietzsche/Plato combo for my personal philosophies (with a heavy dash of stoicism)
Re forms: I find that Plato’s forms are one of the most used mental models I engage with - especially working with software.
