When we say form, we would seem to be referring to the tangible and quite visible shape of a poem. But that’s only the widest concentric circle of what form is. Form is an invisible map. It leads you from poet to poet, century to century, country to country, language to language, culture to culture. At its most inspired, form traces our inspirations, reverences, and innovations; it’s a palimpsest of song and dance. But at its worst it’s a pyrrhic prize: form as value and for its own sake.