Shakespeare
Sonnet 130 and Sonnet 18
Some resources on Shakespeare's sonnets: http://www.shakespeares-sonnets.com/
Online commentary to Sonnet 130: http://www.shakespeares-sonnets.com/130comm.htm (you need to scroll down the page a bit to get to the commentray)
Online commentary to Sonnet 18: http://www.shakespeares-sonnets.com/xviiicomm.htm (you need to scroll down the page a bit to get to the commentray)