Discuss the defects of a summer’s day as highlighted by the poet in Shall I Compare Thee to a Summer’s Day?

In Shakespeare's Sonnet 18, "Shall I Compare Thee to a Summer's Day?", the poet begins by likening his beloved to summer but quickly turns to list the defects of a summer's day in order to prove that the beloved is in fact more lovely and more lasting. These flaws of summer form the heart of the poem's argument.

• Summer is too short. "Summer's lease hath all too short a date." The season passes quickly, so its beauty is fleeting, unlike the enduring beauty of the beloved.
• It is spoilt by rough winds. "Rough winds do shake the darling buds of May." Even the tender blossoms of early summer are battered by harsh weather, so the season is not gentle or perfect.
• It is sometimes too hot. "Sometime too hot the eye of heaven shines." The sun can burn fiercely, making summer uncomfortable rather than pleasant.
• Its brightness is often dimmed. "And often is his gold complexion dimmed." Clouds frequently hide the sun, so summer's glory is inconstant and unreliable.
• Its beauty inevitably fades. "And every fair from fair sometime declines, / By chance or nature's changing course untrimmed." All lovely things in summer lose their beauty in time, whether by accident or by the natural process of decay.

Conclusion. By cataloguing these defects, shortness, rough winds, excessive heat, clouded light and inevitable decline, Shakespeare shows that a summer's day is imperfect and passing. Against this he sets the beloved, whose "eternal summer shall not fade," because it is preserved forever in the poet's "eternal lines" of verse. The defects of summer thus serve to exalt both the beloved and the immortalizing power of poetry.