Final answer:
Literary works often use the theme of pain and suffering to deepen narrative and explore the human condition. This is seen in the references to the Nightingale's song intensifying with pain, as well as using toothache as a metaphor for annoyance or emotional unrest.
Step-by-step explanation:
The passages you've referred to touch upon the thematic linkage between pain, suffering, and the creative process or expression, specifically in literary works. This is evident in the excerpts describing the Nightingale's song growing wilder as it experiences pain, comparing toothache to annoying noises, and mentioning how pain causes unrest in the heart akin to the sea's restlessness.
These are classic examples of using physical or emotional pain to augment the narrative depth and to explore the complexities of the human condition. In some cases, the pain is literal, as in the physical suffering from a thorn or a toothache, while in others, it reflects the metaphorical pain of longing, as shown in the Arthur Symons poem.
These texts use pain as a vehicle for deeper meaning, showcasing how suffering can transform into a catalyst for poignant storytelling or profound revelations about life and love. Through these literary devices, authors convey the universality of pain, transforming a singular personal experience into an aspect of shared human emotion.