Just as poetry and prose are a series of stanzas or sentence, so a musical composition is a succession of definitely organized portions of thought and emotion, in terms of rhythm and sound. In the heart of a composition, to be sure, we often find a great freedom in the phraseology, comparible to blank verse or to a rhapsodic kind of prose.
Page 50. - Quotes from Music: An Art and a Language - The Musical Sentence (Ch. IV)