"And every fair from fair sometimes declines"-Explain.

This line occurs in Shakespeare's sonnet No. 18. The poet here emphasizes the transitoriness of all living object of Nature.

      The poet means the beauty of every beautiful person or object decreases with time. No beautiful thing has a permanent lease of life. It is the law of Nature. The enduring charms of everything are sure to decline someday or other. Nothing exists eternally.Time with its ravages and the power of destructibility annihilates everything. Through this line the poet here establishes the natural fact of the process of decay that every natural phenomenon is subject to. This change occurs because of an accidental ill-luck or through the natural process inherent in all things.