Journey to the West is a really old, pretty well-known book about a guy called Monkey and... some other stuff.
...I'm sure there was more to the story than Monkey.
Journey to the West is one of the single biggest influences on action/adventure genre anime and manga ever. The whole nature of magic and powers in Japanese fiction, the style of formula plots, the style of the protagonist... Not to say there aren't other influences, or that the Japanese (and generally East Asian) mindset isn't part of it generally, but the influence isn't to be underestimated.
Let's just say that if you've ever read or watched anime and manga (of a certain genre), there'll be something familiar about Journey to the West, even if it's not one of the ones that is either an adaptation or wears the influences on its sleeve.
The main character of Journey to the West is a guy called Monkey, as I noted before. That's not really his name, but most people call him that, so don't sweat calling him anything else. He's also known as Stone Monkey, Handsome Monkey King, Protector of the Horses (but don't call him that to his face), Great Sage Equaling Heaven (you can tell he's a modest fellow), and Sun Wukong (Monkey Awakened to Emptiness, or something like that) or Sun the Novice (because technically he's somebody's disciple in Buddhism). The first part of the book describes his bizarre origins (he was given birth to by a rock because it was a special rock in just the right place and oh gosh but that explanation is hilarious) and then describes how he became immortal, gathered strength and power, and ambitiously attempted to conquer the heavens.
For a while, it looked like nobody could stop him. Then the Buddha dropped a mountain on him.
Wait, wasn't the Buddha supposed to be a pacifistic sort of guy?
Anyway, because Monkey is basically completely indestructible, this was only a significant inconvenience instead of insanely lethal like it would be in any remotely normal circumstances, and he spent the next five hundred years with his head peeking out from under the mountain. Eventually, a dude would come along and let him out, and Monkey would have to agree to follow that guy and be his protector on a journey of either 36,000 or 60,000 miles (based on the translation I've read-both figures are cited by the same character at different times, so I find myself wondering which if either is more correct). If he did all that, he would get to be a Buddha.
Oh, yeah, didn't I mention that? There are apparently three thousand Buddhas or potential Buddhas exactly in Journey to the West. I don't know where the figure comes from (and frankly don't care), but I honestly find it pretty hilarious.
Anyway, the guy who frees him is the ostensible protagonist, known by the names Tang Sanzang, Tripitaka (which is a pun on some Buddhist... stuff... that I don't feel competent enough or involved enough to explain), or Xuanzang. He's been recruited by another deity to fetch Buddhist scriptures from India to bring back to China. Unlike Monkey, who is nearly a god incarnate, Sanzang has basically no powers or notable abilities except one: He's the reincarnation of a student of the Buddha, and since he's lived through ten lifetimes wherein he's never failed to follow the precepts of Buddhism, he's the most supernaturally enticing meal/sex object to demons and monsters in the universe.
Yes, I just wrote "meal/sex object." One of the things about him is that if anyone eats of his flesh, they'll live forever and ever and ever. (And they really mean it, too-they talk about the time scale being on the same order of magnitude as the death and rebirth of the world itself. Unless they're being metaphorical, which is perfectly possible.) On the other hand, if a female entity of any stripe successfully seduces him, she'll get the same benefits.
And for reasons presumably having to do with wacky Chinese mysticism, the characters talk about Sanzang losing his virginity in basically exactly the same tone as they talk about his being cooked and eaten. This is possibly the single funniest part of the book, and it happens at least three or four times. Sanzang himself says at some point that if he "loses his primal masculinity" to a woman that he'll basically go to hell forever.
I think that's a bit of an overreaction.
Anyway, obviously Monkey's job is to get Sanzang from China to India so that he can get these scriptures, and he can't let him get eaten or seduced by any of the approximately hundred thousand demons on the way, or let any purely incidental insane royalty, wild animals, bandits, or secretly-evil-demons Taoists hurt him either. (Because apparently the vast majority of Taoists are actually demons.* Who knew?)
Should be easy, right? Among Monkey's many prodigious powers is the ability to fly on clouds at enormous speeds, such that he can cross 30,000 miles in the time it takes him to complete a somersault. At that speed, Monkey could circumnavigate the globe a few hundred times a day or take a tour of the solar system in a reasonable length of time, assuming he didn't need to breathe or use air to move.
Nope. Even though demons can pick Sanzang up with wind or in spirit forms, Monkey can't transport Sanzang magically except to catch him when he's falling and in other need-to-explain-why-Sanzang-didn't-splat sorts of circumstances. Sanzang is apparently magically heavier than Monkey can carry, despite Monkey still being able to fly when he's hundreds of feet tall or when he's carrying and fighting with his magic weapon, a cudgel or staff that weighs nearly nine tons.
Anyway, not only must they walk (or in Sanzang's case ride a horse) the whole way, but they've got to make the journey over a distance considerably larger than the length of the equator, even though China and India are pretty close to each other from the whole "traveling the breadth of the globe" sense. (Apparently, in Journey to the West, India is much further away from China. Don't bother worrying about it.) And even though Monkey once took on armies of 100,000 gods without flinching, he now is regularly challenged by single foes.
...I think Monkey tends to forget that he can be larger than a mountain and can summon a horde of clones of himself, that his weapon can be increased in size and number (yes, increased in number) to match, and he can also take basically any shape, paralyze people or put them to sleep nearly at will, is invulnerable to nearly everything (including a furnace that was supposed to be able to incinerate any immortal being), is stronger than basically anyone, and can see through illusions, pick any lock, and control horses.
Yeah, obviously starting right there the plot tends to have a lot of points that feel like the author is just screwing around trying to make things more interesting.
I also lost count of the number of times that demons had excellent opportunities to immediately devour Sanzang, and said either "Oh, wait, no, if we do that we'll make Monkey really mad, so we'd better wait until we're sure he's given up/defeated first" or "No, wait, this guy is truly a special meal, let's prepare him all nice-like, invite all our relatives, and putz around for a few days first." (The attempted seductions always felt more farcical, especially since the characters treated it with precisely the same urgency.)
And Monkey also has to deal with the fact that some pesky goddess gave Sanzang a torture implement to use on him any time he misbehaves, and Sanzang is wimpy, weepy, easily traumatized, and easy to fool into using said torture implement for no good reason by their supposed allies.
Which brings me to the next point: Basically everyone in this story is a tremendous jerk at least once, regardless of whether they're supposed to be the goodest of the good or the baddest of the bad.
When Monkey is a jerk (or a sociopath), you expect it, because he's basically a sapient wild animal turned god-being. When Sanzang or a Buddha does something jerky, you go "okay, is this supposed to be a vicious parody? Because that felt like a vicious parody moment just now."
There's more characters, plot, and whatnot, but that's what I felt like talking about.
So: Journey to the West. A crazy book, with a lot of padding. (And odd poetry that doesn't translate well.)
And Monkey peeing in the Buddha's hand. There's that, too.
Of course, there's a link to a free (if iffy) translation on the Wikipedia page I linked earlier, so it's not like it'd take a lot of effort to obtain it.
I had a lot of "so that's where that concept came from" moments, which is what I was there for.**
*This is sarcasm. The author often seemed to have something against Taoists, despite frequently paying lip service to the idea of harmonies between China's two big, organized religions.
**Fun fact: If you believe Journey to the West, centipedes have a hundred/thousand eyes.