Style is the material body of lyric poetry, Helen Vendler suggests. To cast off an earlier style is to do an act of violence to the self. Why might a poet do this, adopting a sharply different form? In this exploration of three kinds of break in poetic style, Vendler clarifies the essential connection between style and substance in poetry. Opening perspectives in the work of three very different poets, her study of changes in style yields a view of the interplay of moral, emotional and intellectual forces in a poet's work. Gerard Manley Hopkins' invention of sprung rhythm marks a dramatic break with his early style. Rhythm, Vendler shows us, is at the heart of Hopkins' aesthetic, and sprung rhythm is his symbol for danger, difference and the shock of the beautiful. In Seamus Heaney's work, she identifies clear shifts in grammatical "atmosphere" from one person to the next - from "nounness" to the "betweenness" of an adverbial style - shifts whose moral and political implications come under scrutiny here. And finally Vendler looks at Jorie Graham's departure from short lines to numbered lines to squared long lines of sentences, marking a move from deliberation to cinematic "freeze-framing" to coverage, each with its own meaning in this poet's career. Throughout, Vendler reminds us that what distinguishes successful poetry is a mastery of language at all levels - including the rhythmic, the grammatical and the graphic.