I met a lady in the meads, Full beautiful—a faery's child, Her hair was long, her foot was light, And her eyes were wild.
Why it works
This is a classic ballad stanza: it features an ABCB rhyme scheme (child/wild), alternating lines of tetrameter and trimeter, and the indentation of the second and fourth lines that Keats uses to indicate the shorter beat. The compression here is effective — four lines create a complete and unsettling portrait. The simple language ('her foot was light', 'her eyes were wild') comes straight from the folk tradition, and the strangeness seeps in through that simplicity instead of working against it.