Comparing a lover to much grander physical objects such as roses, the moon or jewels is an example of Petrarchan conceit. Named for the Italian Renaissance poet Petrarch, Petrarchan conceit is a type of metaphor that uses hyperbole to describe the quality of the poet’s love for his mistress.
A famous example of Petrarchan conceit comes from Petrarch’s own poem “Lasciato ài, Morte, senza sole il mondo,” or "Death, you have left the world without a sun." Petrarch introduces the conceit with hyperbole, making his mistress the radiant sun in his universe. Her death has left his heart cold and dark, just like the universe without a sun. Now most often used to tell jokes in light verse, Petrarchan conceit was later practiced and refined by poets such as Edmund Spenser and William Shakespeare.
Like all metaphors, Petrarchan conceit juxtaposes an abstraction – in Petrarch’s case, his beloved mistress – with a concrete object to explain what the abstraction means in a specific context. What distinguishes Petrarchan conceit is that the object of the metaphor is always compared to something wildly out of scale. Further use of overblown language describes the poet’s exquisite suffering over the usually unobtainable object of his love.