Manjiro was afraid, but he said, "My father told me that a person should always put his heart in order before falling asleep. Then he will be unencumbered by fear." Manjiro tried to put his heart in order. He said a sutra—a prayer—for his ancestors, his family, his friends, and for himself. Then he waited for his heart to go back where it belonged instead of jumping all over inside his chest. (2.3.81)
Manjiro's the perfect son precisely because he takes his father's statements and treats them like hard-core principles that he should follow. But how faithful will he be to his father's teachings when he becomes "son" to Captain Whitfield?
Roused from his fever, Jusuke whispered, "As the saying goes: 'Entering the village, obey the village.'" (2.3.31)
What Jusuke says makes sense: If you're going into a new place, you better "obey the village" because, at the very least, it's the polite thing to do. But what's interesting is how Manjiro tries and yet doesn't stick to this principle. Or more to the point, how later, Captain Whitfield encourages Manjiro to do exactly the opposite of this saying…
As a Buddhist, Manjiro had learned that it was wrong to kill—not just people, but living creatures. Of course, Manjiro had killed plenty of fish. In a country like his, surrounded by water and filled with people who needed to eat, it was natural to eat fish. In some villages, whales were sometimes caught. But even a small fish deserved a prayer of gratitude. The fishermen he knew never took fish without remembering to leave grateful offerings at shrines for such purposes. (2.4.76)
This passage comes right after the scene when the sailors capture the whale. Manjiro can't believe how brutal the sailors are to the huge whale, and it's hard not to see his point. Manjiro's philosophy toward animals seems current and modern—you know, eco-friendly and all that. By comparison, the sailors do seem thoughtless about the majesty of the whale.
Manjiro thought, If I'm eating poison, I might as well lick the plate, but he didn't say it. There was no reason to be rude. Instead, he bowed to Denzo and said, "Thank you for reminding me of things I should not forget."
This is the scene when Denzo warns Manjiro that Manjiro is turning into a "barbarian." What's ironic is how deferential and non-"barbaric" Manjiro is to Denzo. He doesn't say what's on his mind, and instead remains super-polite, just the way Denzo expects him to be.
Manjiro had never thought of such things. He had always known what work he would do. Of course, he would have liked to bring honor to his family, and he remembered how he'd once said he wanted to be a samurai. (2.7.36)
By "things," Manjiro means "hopes and dreams"—Captain Whitfield's just asked Manjiro what his are, and Manjiro isn't sure how to respond given that the concept is a little new to him. What his thoughts do bring up is how different his guiding principles were in Japan, with the major one being all about bringing "honor to the family." Now he's trying to figure out what being principled means when the Captain keeps pressing him to express his individualism.
[Captain Whitfield's] an honest and fair-minded man, pious and plainspoken. There be no drink aboard his vessel, and there be no whale chasing on Sundays, neither. And no flogging. He's no hypocrite, like some whose names I could mention. They claim to be godly men, yet treat their crew like dogs. Some ship owners provision their vessels so poorly that a poor sailor can barely keep flesh on his bones. (2.8.7)
Now that's principled. It should be noted that Captain Whitfield principles are couched in his religious background. Manjiro's Japanese focus on taking care of the family doesn't have this same religious emphasis.
"Why would he do a kindness to me?" Manjiro asked.
"Why shouldn't he?"
"Because I am just a boy and he is a grown person. I am a poor nobody and he is a rich important person."
"And why can't a rich man be kind to a poor 'nobody'?" (3.15.31-34)
Manjiro's asking Captain Whitfield why this old guy—a total stranger—would defend Manjiro against a bunch of ignorant white bullies, and what's evident in Captain Whitfield's answer is how different his principle of common goodness is from what Manjiro is used to.
"You will find out that, like Jusuke says, 'the nail that sticks up gets hammered down.'"
Manjiro pointed to the sky. "Look," he said. Pink light rimmed the eastern horizon and ran down onto the sea. "Doesn't it look like the light from another world, spilling through a slightly open door?" (2.11.49-50)
Goemon is telling Manjiro to go with the (Japanese) flow and not go to America—to not be different. It's interesting that Manjiro replies with the opposite of a hard principle, instead offering up a question based on pure wonder at a simple sunrise.
"You deserve a proper upbringing, John, and you shall have it." (3.15.65)
Captain Whitfield is all about committing to John, and that means giving him a farm to live on, a horse to ride, and a mother to raise him. It's a principle that—in abstract—sounds familiar. Sure, these days father-figures might not be promising their sons horses and farms. But they might be promising the kid a stable home and a solid education. Times change but maybe intentions can stay the same.
"These shells are like the people of the world, Okachan," Manjiro said, speaking not just to his mother, but to everyone. "They come from many different places. They come in many different colors and sizes. But they are all beautiful." (5.40.35)
This is the principle that brings Manjiro's story into the 20th century: beauty in diversity. It's a reference to the multiculturalism that we take for granted in our contemporary society.