It's important to note that the beautiful woman is a brunette. What's so special about that, you ask? Well, in Byron's day, conventional English beauties were all pale and blonde. So for him to write a poem that not only praises the beauty of a woman with "raven" (black) hair, but even goes so far as to say that real beauty requires a contrast of light and dark, or day and night, was pretty startling.
- Line 7: This line points out that the woman's beauty is a perfect balance of light and dark – if she were any darker ("one shade the more"), the harmony would get messed up. The line itself is perfectly balanced between opposites: "shade" and "ray," "more" and "less." But if you think about it, the two halves of the line say the same thing: "one shade the more" means, "if she were any darker." But "one ray the less" also means, "if she were any darker." It's like saying, "heads I win, tails you lose" – it sounds like you're saying two opposite things but, really, the meaning of both is the same.
- Line 9: We're so used to hearing dark hair described as "raven" that it's almost a cliché, but it's actually a metaphor.