What is a portion of music divided off by a double bar; a complete musical period or sentence; a movement, or any rounded subdivision of a movement. Their heavenly harps a lower strain began. Dryden called?

strain — (Mus.) A portion of music divided off by a double bar; a complete musical period or sentence; a movement, or any rounded subdivision of a movement. Their heavenly harps a lower strain began. Dryden. (Webster's 1913.)

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