Please summarise and explain "Shall I compare thee to a summer's day?"
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:
Sometime too hot the eye of heaven shines,
And often is his gold complexion dimm'd;
And every fair from fair sometime declines,
By chance or nature's changing course untrimm'd;
But thy eternal summer shall not fade
Nor lose possession of that fair thou owest;
Nor shall Death brag thou wander'st in his shade,
When in eternal lines to time thou growest:
So long as men can breathe or eyes can see,
So long lives this and this gives life to thee.
This is one of many of Shakespeare's sonnets that is in praise of the speaker's love. The speaker starts off with a question, which gives the sonnet its title, and then it is followed by a series of negative answers, as the poet declares reasons why he shouldn't compare his love to a summer's day, because his love is more beautiful than this. The speaker's beloved does bear some resemblances to a summer's day, but only superficial ones. The first two quatrains concentrate on the summer day's imperfections rather than on the loved one. Thus we are told that at times, rough winds shake the buds of summer and also summer is too short. Also, the sun during summer is much too hot at times or it is overcast by clouds. All of these are reasons why the speaker rejects comparing his love to a summer day.
Then, in line 9, comes the turn or shift in focus or thought. The speaker turns from the faulty summer's day to the beloved, and by the end of the third quatrain, the speaker has entirely abandoned the opening comparison. Compared to faulty summer, the "eternal summer" or beauty of the loved one will "not fade". Also, this loved one can really never die, as thanks to Shakespeare, they have immortality in verse.
In Shakespeare's sonnets, the last couplet is often a second turn of great impact, acting as a final summary or explanation of all that came before. In this sonnet the couplet says, perhaps with some exaggeration, that by being addressed in this poem, the beloved person has become immortal.