She walks in beauty, like the night

Byron wrote this lyric for Hebrew Melodies, published in 1815 with music by Isaac Nathan. All the poems in the collection were meant to be sung. The section numbers printed between the stanzas belong to the 1815 edition. Wikisource carries the 1815 text.

Where this text comes fromWhat you are copying is the first two stanzas of three, taken from the 1815 printing. That printing was not a book of poems in the ordinary sense: Nathan issued Hebrew Melodies as sheet music, with the verses set against the notation, so a buyer got something to perform rather than something to read. Wikisource notes that other versions of the collection exist, and the one linked here is that earliest setting. Its Roman stanza numbers are left out of what you type, so the fragment is verse and nothing else, while the elided spellings survive untouched instead of being modernized the way later anthologies quietly do.

What you might not noticeThe fragment keeps the 1815 spellings mellow’d and impair’d. The apostrophe replaces a vowel that would otherwise add a syllable, which mattered when the words had to sit on Nathan’s melody. Source

What it trainsFour apostrophes in 78 words, and every one of them sits between letters rather than at the end of a word: that’s, mellow’d, impair’d, o’er. A hand used to modern prose reaches for that key a beat too late and lands on the following letter instead, which is the single most common error people make on this passage. The other load is Shift. Twelve capitals fall in 437 characters and ten of them open a line rather than a sentence, so the little finger fires on the rhythm of verse, not on the rhythm of full stops. Nothing here is long. The biggest word is cloudless, at nine letters, so the passage tests timing rather than reach.

Read the full text at the publisher: Wikisource