The word '充分' carries a sense of complete adequacy, like when you've had just the right amount of rain to nourish the garden without flooding it. In English, it translates most closely to 'sufficient' or 'adequate,' but with a subtle nuance of contentment—there's no lack, but also no excess.
It's fascinating how this concept appears in 'The Hobbit,' where Bilbo's modest provisions prove perfectly sufficient for his unexpected journey. The Japanese term implies a harmonious balance, different from the bare-minimum connotation 'sufficient' sometimes carries in English. When something is 充分, it meets needs gracefully, like a well-paced story that leaves readers satisfied yet curious.