Final answer:
Poets may depart from an established metric pattern to reflect natural speech or to emphasize certain words, disrupting predictability and enhancing emotional impact.
Step-by-step explanation:
There are two main reasons a poet might choose to deviate from an established metric pattern in a poem. First, the poet may wish to create a more natural or conversational rhythm that better reflects the speech patterns of the poem's voice or character. This can make the poem feel more immediate and personal, as seen in the works of poets like Walt Whitman. Second, breaking the expected meter can serve to emphasize particular words or phrases, disrupt the reader's sense of comfort and predictability, or signal a change in the tone or direction of the poem. For example, the use of a volta in a sonnet marks a shift in thought or emotion. Often, these departures from strict meter serve to enhance the meaning and emotional impact of the words.