“This is an unusual sonnet. It is written in iambic pentameter, but with a strange rhyming scheme: ababa cdc ede fef. In fact, it’s worth reading the words that end the lines. The structure encourages a flowing speech — long at first, shorter afterward, but with a rhyme scheme that connects the phrases. It would seem to split naturally in a quintet and three tercets. Each has a rhyme, which allows for a pleasing conclusion, and yet it is not clear why it should end where it does – it is somewhat abrupt.
This fits Shelley’s dramatic staging. The sonnet has a clear structure — it peaks and then descends — there is a feeling of emptiness or nothingness at the end. The choice of words, the ending of the theme, and the structure of the sonnet conspire to heighten this contradiction — at the end there is talk about the end, yet it comes with a sense of infinite space and time…”
Read more at Percy Shelley, Ozymandias | Ricochet.