Question

Shall I compare thee to a summer's day?

Thou art more lovely and more temperate:

Rough winds do shake the darling buds of May,

And summer's lease hath all too short a date

—“Sonnet 18,”
William Shakespeare

What is the central idea of the first quatrain?

Like summer, romance is beautiful but short-lived.
Beautiful weather makes people fall in love.
The speaker’s beloved is more beautiful than a summer day.
Even rough winds cannot detract from the beauty of summer.

Answer 1

The central idea of the first quatrain is that the speaker's beloved is more beautiful and pleasant than a summer day.