Final answer:
Christina Rossetti's message may center on the nature of love as a powerful, transformative force that often requires personal sacrifice, as well as the subjective perception of beauty beyond the physical realm.
Step-by-step explanation:
The message Christina Rossetti might want to convey to both Andromeda and the reader can be interpreted from the collected excerpts as a profound exploration of love, beauty, and sacrifice. The characters in each excerpt, such as the Nightingale in Oscar Wilde's 'The Nightingale and the Rose', grapple with the nature of love—its demands, conditions, and transformative power. Rossetti's message may dwell on the idea that true love often involves personal sacrifice and that the perception of beauty can transcend the physical to encompass the metaphysical. Moreover, these texts suggest that love is linked intimately not just to joy but also to pain and longing, as evidenced by the Nightingale's ultimate sacrifice for love and the desire for union in the verses from Mary Shelley. There is a consistent theme that love is a powerful force that can give meaning to life, even when it requires giving up one's life or identity.