The contrast between night and day, and dark and light, is the image that sets up the whole poem. But, as we point out in the "What's Up With the Title?" section, this contrast is a startling image: we're not used to comparing beautiful women to "night," we're used to comparing them to "summer's days," like in Shakespeare's Sonnet 18. But Byron turns that convention on its ear, and suggests that it's the harmony of two contrasting opposites, like night and day, or light and dark, that make something (or someone) really beautiful.
- Line 1: This is where the basic simile of the whole poem is established: the beauty of the woman is "like the night."
- Line 2: There isn't any punctuation on the end of the first line so, as you're reading, you should be sure not to pause there. Places where the sentence spills over onto the next line, instead of ending or pausing at the line break, are called enjambments. Check out the alliteration in this line – the repeated cl sounds in "cloudless climes" are very musical, and the repeated s sound, or sibilance, is rather soothing.
- Line 5: "Tender light" is an odd expression, isn't it? "Tender" describes a tactile sensation, while "light" is something you see. Mixing up the senses like this is called synesthesia. It's as though the woman's beauty is so overwhelming that the poet's senses short-circuit, and he feels things he usually sees.
- Line 6: "Heaven" is personified in this line – after all, the sky can't really "deny" anyone anything, so the poet is giving it attributes of a human being.