Here's how it typically works:
* First Quatrain (4 lines): Introduces the main idea, topic, or problem.
* Second Quatrain (4 lines): Develops the idea further, explores related concepts, or adds complexity.
* Third Quatrain (4 lines): Often introduces a shift in perspective, a twist, or a solution. This is where the "volta" (turn) occurs.
* Couplet (2 lines): Provides a concluding thought, resolution, or reflection on the overall theme.
Example:
Let's look at Shakespeare's Sonnet 18, "Shall I compare thee to a summer's day?"
* First Quatrain: Introduces the beauty of the beloved and compares them to a summer's day.
* Second Quatrain: Elaborates on the beloved's beauty, emphasizing its lasting quality.
* Third Quatrain: The "volta" occurs here. The speaker shifts from comparing the beloved to nature to emphasizing their eternal beauty through poetry.
* Couplet: The sonnet concludes with a strong statement about the beloved's immortal beauty.
Therefore, the shift in focus after the first stanza is crucial for the development and climax of the sonnet's message. It allows for the exploration of different angles and perspectives, ultimately leading to a satisfying resolution or reflection in the final couplet.