Complex sentence: After leaving the Island of the Blessed, they deliver a letter to Calypso given to them by Odysseus explaining that he wishes he had stayed with her so he could have lived eternally.
Split into simpler sentences: After leaving the Island of the Blessed, they deliver a letter to Calypso. The letter, given to them by Odysseus, explains that he wishes he had stayed with her so he could have lived eternally.