If you want to read some ancient philosophy directly, Plato's Symposium is a fun start. It is a bunch of guys staying up all night getting drunk and sharing their theories about love. And yet it is philosophy. Of course Socrates gets the last word---sort of. Also don't miss the point that one of the speeches is by Aristophanes, a comedian.
If it's the ancient Greek world that is inspiring you, maybe read Homer or Herodotus. Some quick notes there:
The Iliad - This takes place in the ninth year of the ten-year-long Trojan War. The Greeks are a loose alliance of kings, led by Agamemnon, who have sailed to Troy and are still trying to overcome its defenses. Their best warrior, Achilles, gets mad at Agamemnon and decides to quit fighting, and everything starts to fall apart. The poem is his story, although in many ways it is broader, covering lots of other heroes. So you have simultaneously the "big picture" of the war and the "little picture" of Achilles (plus some other major figures).
Most readers find this book more challenging than the Odyssey, because there is less fun adventure. It can be monotonous. It is chapter after chapter of "And X threw his bronze spear and it struck Y between the teeth and came out the back of his neck, and he fell into the dust and his armor clashed around him." But it may not be a bad monotony. Have you listened to Symphony of Sorrowful Songs by Górecki? It is like that. But if you get to the end, and think about Achilles's story, it is so good.
The Odyssey - Now the Trojan War is over, and the heroes are going home. This is about how the Greek hero Odysseus gets lost, and spends another 10 years wandering. It spends some chapters on his wife and just-now-grown-up son, who are fending off the crowd of suitors who want to marry his wife and steal his estate. It follows Odysseus through his wild adventures---the most fun and memorable part of the book. And it tells of how he finally returns and defeats the suitors. (Contrary to what people usually remember, that is actually half the book.)
These books are striking in how opposite they are, and in many ways their style reflects their protagonist. Achilles is simple and straightforward, and the book is too. It has that monotony, and it basically starts at the beginning and plows forward to the end. Odysseus on the other hand is "wily" or "tricky", full of lies and schemes. (He was the inventor of the Trojan Horse.) And the book jumps all over, with flashbacks and stories-within-the-story. Multiple chapters are told by Odysseus himself. Coincidentally they are the most mythical, making you wonder if they are lies too. :-)
Some people even suggest that the first sentence---maybe even the first word---of each poem contains the rest of the story. For the Iliad it is Achilles's μῆνιν: wrath (or maybe sullenness---he is practically a teenager (or was when he came to Troy)). For the Odyssey it's ἄνδρα: the man: Odysseus.
For Homer there are lots of translations. Lattimore is great and close to the Greek, but I find Fitzgerald's to be the most enjoyable. He gives up some precision to get more poetry, and it's like reading to a soundtrack.
The Histories of Herodotus are fun too, but more history than literature. If you get The Landmark Herodotus, the maps and notes help a lot. I would just be aware of what you're reading: ostensibly this is a history of the Persian War, and that is the thread that connects everything together (like Achilles in the Iliad), but Herodotus's main movement is the digression. Chapter 2 is all about Egypt (its history, culture, etc.). Chapter 3 is all about the East. Chapter 4 is all about Scythia. You get the idea. It's like he is trying to catalog everything known or said about the world around him.
Herodotus was part of a "rationalist" movement in ancient Greece, along with the early philosophers. He is one of the first to write in prose instead of poetry. He is called the First Historian in part because he gives his sources. Sometimes he'll give several versions of something, and leave it up to you to decide. But that doesn't mean he is rational by our standards. There are plenty of myths and legends and wild stories. You will need some patience to finish this book, and a guide would help to draw out the gems, but it is pretty wonderful if you're paying attention.
Good luck, and enjoy your reading! :-)
